Footage has emerged of a dawn immigration enforcement operation by six officers, showing a “distressing” and “intimidating” sequence of events.

The visit to the home of a woman who was in the process of regularising her visa status has raised fresh questions about the fairness and efficiency of Home Office policy.

An enforcement team visited the home of Zixuan Qu and her fiance, Duncan Watkinson, at around 5.30am on 1 May. They searched the property and told Qu she had “no leave to remain in the UK” and that she had been classified as an “immigration offender”.

After 25 minutes in the couple’s home, the officials appeared to acknowledge an error had been made and retreated, leaving Qu terrified and Watkinson in tears.

The couple are angry that immigration staff carrying handcuffs descended on their home in an apparent attempt to take Qu into detention, when they believe she has done nothing wrong. Qu said she had never been notified that there might be a problem and believed that her visa application was still in the process of being considered.

Qu, 29, came to the UK in 2010, after winning a scholarship to study health and social care in London. Representatives from a British college had visited her nursing school in Szechuan province, China, encouraging students to apply for their course, explaining that the NHS needed to recruit healthcare workers. Qu was the only student to pass the necessary exams, and she moved to the UK.

Facebook Twitter Pinterest Zixuan Qu and her fiance, Duncan Watkinson, in their home in London. Photograph: Jill Mead/The Guardian

In 2014 she submitted an application to extend her student visa. She received a letter from the Home Office saying it was considering her case, but it explained that her application, like thousands of other visa applications at the time, was complicated by a government decision to suspend an English-language proficiency test that she and tens of thousands of other students had had to take as part of their student visa applications, amid concerns over irregularities in the test results nationally.

The letter stated: “Please be assured that we will make a decision on your case as quickly as possible … We will not take removal action as a result of the contents of this letter.”

The crisis over the TOEIC English-language exam resulted in around 45,000 students’ visas being cancelled and many of them being deported through no fault of their own, because of suspicions about the way some colleges were administering the officially accredited test.

After that letter in 2014, Qu says, she received no further communication from the Home Office until a letter arrived a few days after the visit this month, informing her that she was “liable for removal”. She had hired a lawyer in 2015 to help her because she was worried about the silence and the ongoing uncertainty. When her lawyers contacted the Home Office on her behalf last year, they were told there were no updates.

The Home Office has held her passport since 2014, as officials processed her application. Qu, who switched to studying for a business degree after getting her health and social care qualification, is upset that this has meant she has not been able to travel home to visit her elderly grandparents who brought her up.

Qu and Watkinson, 37, planned to get married last September and they booked a wedding venue and sent out invitations. However, the event had be cancelled at the last minute because without Qu’s passport, the wedding could not go ahead. Two requests sent by her lawyer to the Home Office for a certified copy of the passport so they could register the marriage went unanswered.

Anxious to resolve the situation, in April Qu and Watkinson paid more than £2,000 for a Home Office “one-day premium” visa processing service, and they were given an appointment on 16 May.

During the officials’ visit to their home, Watkinson repeatedly expressed his confusion about why Qu was being targeted two weeks before this premium-service appointment. Initially he was told by staff that they were there because, according to their information, Qu had been classified as an immigration offender. By the end of the visit he was told the officials had found a note of the appointment, and the team agreed to leave.

Watkinson said staff began their operation in a very intimidating manner. “The initial announcement that they’re there is an incredible loud banging on the doors and windows. The reaction turns from complete shock and surprise to confusion, because you haven’t done anything wrong,” he said.

“They came in without showing me anything. I opened the door and the first thing that happened was one of the officers put their hands on my chest and pushed me back into the room. Following him were six or seven others.”

The officers were calm and well-mannered throughout the course of the raid and the couple have no criticism of their conduct; they said they felt sorry for them, because they were just doing their jobs.

He said he felt angry and distressed afterwards. “I sat down on the floor and started to cry; the adrenaline is so high when you’re facing it. After they’ve gone, I broke down, [wondering]: ‘Why did they do that? What have we done wrong? Have we missed something? Have we made a mistake?’”

If Watkinson had not been there, Qu said, she would not have had the confidence to stand up to the immigration team. “I thought I’m going to get detained and I was going to get removed from the UK away from my fiance … All my adult life was here and they’ll just take everything away from me and send me back to China.”

Qu is unhappy that she has exposed Watkinson and his family to all the worry and expense caused by her immigration status. She is also unhappy that she has not been able to work for years because of uncertainty about her visa status, leaving her financially dependent on her fiance.

Every year there are an estimated 6,000 immigration visits to workplaces in the UK, according to a Home Office intelligence document leaked in 2014. Every month there are dozens of immigration visits to people’s homes. EU human rights group have campaigned for governments to stop using dawn raids in immigration cases, but in the UK they remain relatively common.

A Home Office spokesman said: “Ms Qu has overstayed her visa since January 2014. Her last removal notice was served in January 2018. Ms Qu had not made an application to the Home Office simply by booking and paying for the appointment. The application is not made until she actually turns up to the appointment and submits the application.”

Watkinson said he was puzzled by this response. “We have never received any notice of refusal from the Home Office dated January 18 or any other date, and neither has our lawyer,” he said.

Qu’s representative at the immigration advice firm Visa Direct said: “Visa Direct has never received any response to any of our communications with the Home Office in relation to Ms Qu’s visa application submitted in 2014.”

He was also puzzled by the suggestion that removal notices had been sent to Qu, adding that it was normal practice for the Home Office to send this kind of document by recorded delivery, so it was unlikely that Home Office notification letters had gone to the wrong address.