Foreign care staff invited to the UK to help fix a chronic worker shortage are being “exploited on a grand scale”, a trade union has said, after it emerged some had been effectively paid as little as £5 an hour and charged thousands of pounds in unexpected fees.

One worker from Botswana being helped by the healthcare union Unison said she worked in domiciliary care from 6am to 10pm six days a week but was paid less than half the legal minimum. The Wiltshire company laid her off after losing the council care contract and now she fears deportation. Another company in Cambridgeshire, which recruited from abroad, shut last week, leaving workers fearing deportation.

In another case, cited by the union, an employer demanded £4,000 for “training costs” when a migrant care worker tried to leave for a job in the NHS and a third care worker was hit with hidden administration fees including £395 for a “cultural induction”.

The incidents have come to light amid reports the immigration minister, Robert Jenrick, has drawn up options to curb immigration, including banning workers from bringing dependants, or restricting them to one relative.

The Home Office extended skilled worker visas to foreign care workers in February 2022 to help fill 165,000 social care vacancies, which were leaving some of the UK’s most vulnerable people struggling for help.

Most recruits have come from Nigeria, India and Zimbabwe, according to Skills for Care, a government-funded agency. Since the Home Office added care workers to the shortage occupation list, 14% of care workers in England are now from non-EU countries (excluding the UK), while 7% are from the EU.

The Unison general secretary, Christina McAnea, said: “The care system would implode without migrant care staff. Demonising these workers will do nothing to solve the social care crisis.”

About 78,000 people secured visas to come and work in social care in the year to June 2023. But the rules mean that if a worker is laid off, or their employer closes down they must find a new sponsoring employer within 60 days or face deportation. This gives employers additional power over workers and Unison is urging the government to allow them more time to find new work.

Annie, a care worker from Botswana, was one of the first to arrive under the scheme, but said her private agency only paid for the hours that she was caring for clients in their homes in Wiltshire and Somerset.

It meant she worked 15-hour days, including waiting for appointments and driving between clients, but was only paid for about six hours. She said the employer also withheld much of her wages for three consecutive months, only repaying her later. It also required her to share a room with a stranger.

“I have been living with anxiety since I arrived here,” she said. “I have problems trusting anyone because they built a fear in me when I arrived.”

She has a new job, but her current employer has not yet agreed to sponsor her visa and the 60-day deadline falls this week, leaving her worried about whether she will be able to stay in the UK. She has sold up many of her possessions in Botswana.

McAnea said: “Overseas care workers have been encouraged to come here to support those most in need, only for some employers to treat them as expendable.