London(CNN) Four years ago, thousands of foreigners living in the UK, many of them students, began receiving letters ordering them to leave the country or face deportation.
For others, the first sign that their visa had been revoked was a knock on the door from immigration officials bearing an arrest warrant.
These students, many from India and nearby countries, were accused of cheating on an English language test known as TOEIC by using someone else to sit their speaking exam.
It was one of several tests approved by the British government for non-EU citizens applying for a visa to study or work in the UK. Those who are granted a visa and move to the UK must retake the test every two years.
In the first two years after the accusations emerged, the UK Home Office revoked or refused more than 28,000 visas and deported more than 4,600 people on the basis of the claims, according to a 2016 report by the parliamentary Home Affairs Committee, a cross-party group of members of Parliament who scrutinize the department's policies.
But the Home Office is facing serious allegations of wrongdoing from MPs and senior judges regarding its handling of the issue.
It is not the only set of accusations currently levelled at the department, which has been accused of subjecting legal migrants to its "hostile environment" policy, which was designed to target people in the country illegally.
Dozens of cases have emerged recently of Afghan interpreters who served with the British military and members of the so-called Windrush generation from Commonwealth countries being wrongly deported or threatened with removal -- and the Home Affairs Committee is now calling for "root and branch reform" of the Home Office.
Home Secretary Sajid Javid and Prime Minister Theresa May -- who ran the Home Office from 2010 to 2016 -- will come under renewed pressure to answer the TOEIC allegations Tuesday, when dozens of students accused of cheating and now battling those accusations in court attend the Houses of Parliament for the launch of a report compiled by London-based charity Migrant Voice.
Those affected were given no chance to retake the test, no access to the evidence against them for several years and no chance to appeal the decision from within the UK.
While a number of instances of fraud have been proved, many court cases have exposed the possibility of errors in the process of identifying suspected fraudsters and significant flaws in the government's arguments, with one judge finding "multiple frailties" in the evidence presented by the Home Office.
The Home Affairs Committee report was even more critical, concluding that the situation "raises serious questions about the conduct of the Home Office."
In a statement to CNN, a Home Office spokesperson defended the department's "robust" response to the initial allegations, which was described as "measured and proportionate."
The Home Office spokesperson did not respond to questions about the strength of evidence presented by the government in court.
RJ, 28, is one of dozens of foreign students who had their visas revoked and were thrown out of college but stayed in the UK to fight the accusation in court.
Many of them are now winning the right to stay in the UK and challenge the accusations directly.
Fearful that his case would be jeopardized if he revealed his full name, RJ requested that CNN use only his initials.
He, like all of those still battling, is considered an illegal immigrant, with no right to study, work, drive, claim benefits, rent a house or use the National Health Service.
Four years on and living in limbo, RJ feels like he has lost everything.
"I had dreams," he said, explaining how he arrived from his home in Jammu and Kashmir, northern India, in 2008. "I wanted to be something by this age."
"My father gave his life, he worked hard to provide me a bright future and this is the future I'm getting," he said. "I understand if I've done something wrong... But I haven't done nothing and still, the trauma, the pain we have to go through."
"Life has come to a halt," he added.
He said he suffers from depression and anxiety as a result of the ordeal, for which he is taking medication and seeing a therapist.
Asked why he doesn't go back to India, he spoke of the pride he felt in coming to study in the UK and the shame of returning home with nothing except an allegation of fraud and a pile of debt (he said he has spent more than £50,000, or $66,000, on tuition and legal fees).
"It was known that Britain is the place where you can get a world-renowned degree," he said. "And I didn't achieve nothing. It's shameful."
Shabbir Islam, 32, from Pakistan, also denies cheating. He stayed in the UK to fight the accusation, despite initially being arrested and held in detention for more than a month, he said. Like RJ, he finds himself still in limbo.
"I lost my job, I lost my girlfriend," Islam said. "You don't have money in your pocket, you can't work, your social life is, sorry to say, totally f***ed."
The stress is almost unbearable, he said. "When I came, I was a very young and handsome guy," Islam said with a wry smile. "If I go back to my country, even my mum, she won't recognize me."
"A very large number of people have suffered a grave injustice," Labour MP Stephen Timms, who has been advocating in Parliament on the students' behalf since 2014, told CNN. "To leave people so desperately out of pocket with this stain on their reputation... for me that's not acceptable."
The students' problems began in February 2014 when a BBC documentary revealed systematic cheating at two colleges in London on the TOEIC English language test.
Two months after the documentary aired, the Home Office ended its contract with Educational Testing Service (ETS), the global education provider that set the TOEIC exams, and launched a criminal investigation into the organization.
ETS did not respond to multiple requests for comment.
In a bid to discover how many students had cheated, ETS used voice biometrics to analyze tens of thousands of recorded oral tests, looking for repeated voices.
After further human checks, ETS concluded that there was evidence of proxy test-taking in nearly 34,000 cases. A further 22,000 tests were considered "questionable" -- the students who took those tests were offered the chance to resit, according to the Home Office.
Speaking in perfect English with an East London accent, RJ explains how he had taken several English language tests in the years prior to 2014, passing each one, and had even sat an extra exam after he heard about the allegations of fraud at ETS centers, hoping to shore up his case in the face of any accusations.
But, like thousands of others, he received a letter from the Home Office informing him of his status as an "illegal entrant/person" and a second a few days later warning of his imminent removal.
RJ had no right of appeal -- except from outside the UK.
That's one of the many aspects of the situation that angers Patrick Lewis, an immigration lawyer who has represented around eight of those affected, and won each one of those cases.
When an individual's ability to speak English is so key to the case, their presence in court is vital, he argued.
Last June, five Supreme Court judges concluded in a ruling unrelated to the ETS issue that an out-of-country appeal was not a fair or effective way for a person to appeal a deportation order.
Referring to that ruling -- which, unlike the ETS cases, related to two individuals convicted of serious offenses -- three judges considering the case of a TOEIC student concluded that the student's rights would not be satisfied if forced to appeal from outside the UK.
It was a significant ruling, but meaningless for the thousands of people who have already left the UK or been deported.
"I find it extraordinary that this has occurred in the UK," said Lewis. "It seems to go against everything that we take for granted -- that there is due process, that a person can put forward evidence to rebut serious allegations. Thousands of individuals were denied that most basic of rights."
"It has led to incredible hardship," he added. "These are individuals of good character who were investing in their future and had everything taken away."
Many of those who stayed in the UK say they were refused access to the recording, the critical piece of evidence against them. The Home Affairs Committee, highly critical of the lack of evidence presented by ETS or the Home Office in court, described the refusal of ETS to provide the recordings as "mildly astonishing."
Wahidur Rahman, 28, from Bangladesh, described how he asked both ETS and the Home Office for the recording in the months after the allegation but each claimed it was the other's responsibility.
"Can you see how unfair it is?" Rahman said. "You accuse me of something but you can't show me the evidence."
"Access to the voice samples was not denied to anyone," a Home Office spokesperson said in a statement to CNN, adding that individuals were told to request the recording from ETS.
According to Lewis and to court records, ETS has now begun releasing the recordings when asked -- but again, that comes too late for many.
RJ is desperate to clear his name before returning home to India. He said he would rather "jump out of the plane" than go home with the accusation intact. "It's pride we all live for," he added.
It's been more than four years since he saw his family, since he won't be allowed to return to the UK with his current status.
But the thought of returning home saddens him too. He said he has lost touch with his friends, most of whom are already married with children; the gulf feels too big, he explained.
His relationship with his family has been badly affected too. "When I call my father, the first 10 seconds are normal, then it's all shouting," RJ said.
The situation is becoming unbearable, he said: "I'm just living in a cage."