One of Britain’s biggest providers of agency care workers has been fining staff who phone in sick £50, raising concerns that frontline employees are being forced to turn up for shifts when they are not fit for work and risk spreading illnesses to vulnerable patients.

An investigation by the Guardian has uncovered evidence of cases in which Newcross Healthcare Solutions has failed to pay its employees if they cancel shifts because of illness without 24 hours’ notice, and has also docked money from their pay.

The firm, which employs 7,000 staff across 63 branches providing temporary nurses and care workers for hospitals and residential and nursing homes, made a pre-tax profit of £21m and paid directors an equity dividend of £17m in 2017.

After being contacted by the Guardian, Newcross Healthcare announced it would be scrapping the £50 charge by April 2019. The firm, which said it could not comment on individual cases, also denied workers had wages docked when they were “genuinely ill”, but dozens of examples seen by the Guardian suggest otherwise.

Among the allegations of the £50 charge has been used against employees with legitimate health issues are:

An employee who said they they were laughed at on the phone and had their wages docked after crashing their car on the way to a shift, suffering serious injuries.

A pregnant worker who had to call in sick with vertigo meaning she was unable to drive an hour and a half to a shift was fined wages even after obtaining a doctor’s note.

A former worker claimed staff incurred the charge after missing shifts because of a cancer scare.

The shadow minister for social care, Barbara Keeley, said the case was “symptomatic of our broken care system”. “Good care quality depends on workers with good terms and conditions, but in hollowing out our social care system through relentless cuts to council budgets, this government has empowered irresponsible providers that are driving down workers’ conditions and at the same time damaging the quality of care,” she said.

The Unison assistant general secretary, Christina McAnea, said: “Care staff can’t avoid being exposed to germs and health hazards. This practice seems highly dubious and we’ll be investigating.”

Eileen Chubb, the founder of Compassion in Care, a whistleblowing charity that campaigns to improve care, said Newcross care workers concerned about the policy had contacted her.

“It is obscene that a company making millions of pounds in profit should be docking £50 from the wages of carers who phone in sick,” she said. “It raises the serious risk that carers are turning up for work when they’re not well, putting vulnerable elderly people at risk. It’s an accident waiting to happen.

“They’re leaving staff in a position where they’ve got to choose between going into work when they’re unwell or have their pay docked. People may well be tempted to go to work when they’re not fit to, because they can’t afford to lose the money. When someone is on very low pay, £50 is a lot of money.”

The firm, which also provides staff for prisons, hospitals and schools, is owned by Newcross Nursing Group Ltd, which in turn is owned and controlled by Beluga Rock Holdings Ltd, a firm registered in the tax haven of Gibraltar.

The ultimate controlling parties are the Newcross founders Stephen Pattrick and Michelle Gorringe, who live in Gibraltar. Pattrick, who is pictured on social media smoking cigars and shooting, is also the chief executive of the motorsports team Bullitt Racing and has driven for the team. The Bullitt Racing website says that his “success in business” has enabled him to “indulge in his motor racing hobby” and “fervour for speed”.

The firm’s employee handbook confirms the existence of the charge, stating under “absences and sickness”: “It is important that you provide as much notice of any planned or unplanned absence as soon as possible as it can cause considerable difficulty and expense when trying to find alternative cover. Where you have accepted an assignment and you subsequently fail to attend without reasonable notice or valid reason, we reserve the right to make an administration charge [which may be recovered from you in accordance with clause 6.14 of your contract of employment].”

The Guardian, however, has uncovered a series of examples in which workers claim that they have been charged a fee even when giving valid reasons. The jobs websites Indeed and Glassdoor are flooded with dozens of negative reviews written by furious current and former employees of the agency complaining about the charge.

They include one current employee in south-west England who claimed they were fined £50 after crashing their car on the way to a shift. They wrote in November: “One time I crashed my car on the way to a shift, sustaining injuries to my spine. I rang Newcross to tell them I wouldn’t be able to attend, instead going to hospital. They laughed on the phone, then told me: ‘Thank you for losing us a client,’ and went on to to charge me £50. I was disgusted.”

A former employee from Glasgow wrote in October: “Worked with Newcross from 2011 until 2018 and discarded without a second thought, had no support or loyalty, cared more for their contracts rather than the staff. You incur a £50 charge for missed shifts even when this is for a cancer scare, disgusting agency whose only concern is to make money and offer shifts [to] their favourite staff.”

In October, a former employee in Wales wrote: “I recently found out I was pregnant and had to call in sick twice for being poorly. One occasion being I had vertigo and couldn’t drive to my 1 hour and 30 min drive shift. My partner took me to the doctors and I got a doctor’s note and tablets to take. I was still charged £50. I think the company is appalling and I am considering taking it further!”

Rakesh Patel, the head of employment rights strategy at Thompsons Solicitors, said: “It’s pretty outrageous if the company is penalising workers for taking unplanned sick leave. By its very nature, sickness absence is often unplanned.”

A Newcross Healthcare spokesman said the firm was not an agency, pointing out that it employs staff on permanent contracts and offers guaranteed hours. The firm’s own Facebook page, however, describes it as an employment agency.

A spokesman said: “It is an administration charge applied if staff pull out of a shift with less than 24 hours’ notice for whatever reason. All of our employees sign up to this legally binding agreement as part of their contract of employment.

“The 24-hour protocol is to ensure there is no disruption in patient care and to protect those who rely on our employees to attend their shifts once they have accepted them. Patient care is absolutely paramount to us and we take very seriously our commitment to deliver for our clients and to follow Care Quality CommissionCQC, Care Inspectorate [Scotland] and CI and CIW Care Inspectorate Wales regulations.

“The administration charge is being phased out and will cease in April 2019. We are rolling out a new internal app that allows our staff to auto assign shifts. This technology will enable us to fill any shifts that become available quickly and efficiently.

“At present, if someone is genuinely ill, they should not be working. Each cancellation is reviewed by a line manager and if there is a genuine reason for absence, we do not administer a charge. For instance, in 90% of cases in the past calendar year, this administration charge wasn’t applied. There is also an appeal process for employees who feel it has been incorrectly administered. We have appeals that have been successful and unsuccessful.”

The firm said nine of its 11 branches regulated by the CQC are rated good or outstanding. The Guardian understands the £50 charge has been in place since at least 2014, but Newcross was unable to say how long it had been in operation.