Just read on the BBC that a 'probe' has been launched into Expert Medicals by the CMA:
https://www.bbc.co.uk/news/business-58439049
Like a number of users, I opted for their £28+7.99 option for my recent trip, posted our tests out to them on Weds and not yet heard anything... could well receive results this evening but judging by the story on the beeb, it's unlikely!
It'll be interesting to see whether refunds will follow for late results etc. - their website explicitly states they're not liable, and I'm not sure if it's a three day turnaround from posting or receipt, but they've had over £100 from me to do a lateral flow test - given it's all pretty much a government backed scam, I hope there is some recovery for travellers, but not holding my breath!