The competition watchdog has launched a probe into PCR tester Dante Labs, which has completed four million tests since Covid began, over worries it might not be delivering tests on time or at all.
The Competition and Markets Authority (CMA) said Dante could be breaking the law and treating customers unfairly.
It said the company might not be delivering PCR tests or results on time or at all, and failing to respond to complaints or provide proper customer service.
The company might also be refusing or delaying requested refunds and using terms and conditions which unfairly limit consumers’ rights.
Dante, which said it is “disappointed” by the probe, is on a Government list for providers of tests to enter England after traveling abroad.
CMA chief executive Andrea Coscelli said: “People are paying significant amounts of money for these crucial PCR tests and there is no excuse for poor or non-existent service.
“While the rules in England around PCR testing for travel are due to change in the coming weeks, the CMA will continue to investigate whether companies are breaking the law.
“Firms should be aware that if we find evidence of the law being broken, we will not hesitate to take action.”
The CMA said it had received complaints about Dante directly and others through Citizens Advice.
Dante said: “While the overwhelming majority of our customers have received a timely and cost-effective service, we recognise the challenges faced by a small proportion of those who have purchased our tests. We have invested significantly in our customer service operation to improve our overall delivery in the face of huge demand.
“We are disappointed by the CMA’s decision to launch this investigation without prior consultation. Nevertheless, we will co-operate fully by providing all and any information in line with our commitment to full transparency.”