A man said his family's stay in a quarantine hotel was their "worst-ever experience" after his wife and baby son were left needing hospital treatment.
Abby Pansegrauw, 34, and her son, one, fell ill as a result of food they ate while at the hotel, doctors believe.
Her husband, Etienne, said staying at the Novotel London Heathrow Airport in April was like being in a prison.
The hotel said it was "unlikely" it caused the food poisoning and it was "disappointed" to hear their views.
The family of five, which split their time between London and Swindon, Wiltshire, paid £2,400 for their 10-day stay at the hotel after paying £2,000 for their flights back to the UK from South Africa's Eastern Cape.
They had been stranded in the country for four months after it was placed on the UK's red list, initially travelling for a short trip to see family in December.
Mr Pansegrauw, 41 said his wife "ended up on a drip because she was so dehydrated".
"The hotel refused to acknowledge it and refused to apologise," he said.
"I would say it's the worst experience I've ever had - not just hotel experience."
The pub owner added there was "nothing healthy" for his children to eat and they were refused requests for "simple things" like spaghetti.
"I've never been in prison before, but [the hotel conditions] felt like that was the closest thing to it," Mr Pansegrauw said.
A spokesperson for Novotel said that the company "conducted a detailed investigation" and said an attending paramedic "found food poisoning to be unlikely with there being no other cases at the hotel".
Quarantine hotels are organised on behalf of the UK government by Corporate Travel Management (CTM).
A CTM spokesperson said it had made bookings for more than 27,900 people returning to the UK, and received complaints about the service in hotel quarantine for 1.6% of them.
A spokesperson for Novotel said the company was "disappointed" to hear the Pansegrauws' feedback and said that of other guests had been "overwhelmingly positive".
"We of course recognise these are challenging circumstances and we have done all we can to make the experience as comfortable as possible for our guests, including enabling guests to order take-away food deliveries during their stay," the spokesperson said.
A Department of Health spokesperson said: "Our top priority has always been protecting the public and the robust border and testing regime we have in place is helping minimise the risk of new variants coming into the UK.
"The government continues to ensure every person in quarantine gets the support they need, and all managed quarantine facilities are accommodating the vast majority of people's requirements."