In an unexpected U-turn, the Home Office has granted a visa to a woman it had previously classified as an immigration offender, just 24 hours after video footage of a distressing dawn raid on her home was published by the Guardian.

Zixuan Qu, 29, who submitted an application to extend her student visa over four years ago, has been granted leave to remain in the UK for a further five years.

For the past four years, the Home Office has been sitting on her application, and has held her passport, preventing her from going back to China to visit her grandparents, who brought her up. She was forced to cancel her wedding because she was unable to register the marriage without a passport.

An immigration enforcement team of about six officers visited the home Qu shares with her fiance Duncan Watkinson, 37, at 5.30am on 1 May. Immigration staff told Qu she had “no leave to remain in the UK” and that she had been classified as an “immigration offender”.

Qu and Watkinson were surprised to have been visited by immigration officers because they believed they were in the process of finalising Qu’s protracted attempts to extend her student visa. They had already paid over £2,000 for the Home Office “One Day Premium” visa processing service appointment.

After 25 minutes in the couple’s home the officers realised that this appointment was pending, acknowledged a mistake had been made, and left the flat, leaving Qu terrified and Watkinson in tears.

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

Qu said she was extremely relieved at the news that her visa had been granted, but expressed incredulity that an application which had been pending for such a long time had been resolved so swiftly.

“I immediately called my grandparents in China. The first thing that I’m going to do is book my flight to visit them. They were crying,” Qu said. She said both she and her fiance were in tears in the cafe of Lunar House immigration headquarters in Croydon after receiving the news.

The couple said they plan now to reschedule the wedding they were forced to cancel last September.

“I felt utter relief and disbelief, mixed ever so slightly with a sense of guilt that there are other so many cases like us still waiting for an answer. We could see other cases there in the waiting room,” Watkinson said. He wondered if the media exposure of the dawn immigration enforcement action had contributed to the speed with which the visa was granted.

“I would like to think they would have made the same decisions without the video; we have met all the requirements, but we don’t know,” he said. The immigration adviser, whom they paid to assist them, said it was unusual for a case to be pushed through on one day.

Qu said there was no apology for the distressing immigration enforcement action nor any apology for the four-year delay, during which time she has not been allowed to work or study.

“I am just really relieved. I’m not an angry person. It could have been done four years ago. It took four years of my life, my money … I couldn’t work; I couldn’t go home to visit my family … but today I just feel happy,” she said.

Watkinson said he was angry that the politicians who designed the immigration policies “never see people at Lunar House; it’s not on their radar”.

“All these hostile immigration policies, they come from the top. The workers in Lunar House, they have to deal with the human element, they’re the people who have to mop up the mess,” he said. “Why were we put through all this, if this is the end result? There is still that anger – the entire policy, the entire system is broken.”

On Tuesday, the Home Office said Qu had overstayed her visa since January 2014, and had been served with a number of removal notices, the last in January 2018. Qu said she had never received a removal notice.

A Home Office spokesperson said on Wednesday: “We are pleased to confirm that we met with Ms Qu this morning and she has been granted leave to remain.”