The competition watchdog will continue to monitor the behaviour of PCR test providers after one firm under investigation was ordered to refund all disgruntled customers within 21 days.

The Competition and Markets Authority (CMA) said Dante Labs, the subject of a probe last September, has committed to improve its practices following a number of complaints from travellers who either didn’t receive their tests or results yet were refused refunds.

An investigation into another provider, Expert Medicals, is ongoing, while others have been told to step up their game or face enforcement action.

CMA Chief Executive Andrea Coscelli said:  “No PCR testing firm is exempt from the rules and our action to secure these refunds and other changes shows that we will not tolerate poor business practices.

“While travel rules to the UK may have changed, those people who still require PCR tests to travel abroad shouldn’t have to waste money on late results or tests that don’t arrive.

“It is crucial that all PCR providers treat people fairly, being clear on price and timings and providing refunds where they are due.”

Dante Labs has vowed to complete its review of complaints and ensure refunds are paid in full.

The CMA said the company has already refunded thousands of customers “and under the terms of the undertakings, any outstanding refunds must be paid within 21 days”.

Dante has been told to provide an update to the CMA in three months.

The investigation into Dante Labs was part of a wider probe to investigate reports that travellers were being ripped off by providers.

The CMA issued letters to 25 providers warning them to review their terms and conditions – and other practices – or risk enforcement action.

Randox was among the firms which changed its business practices while a formal investigation opened into another provider, Expert Medicals. An update will be provided ‘in due course’, the CMA said.