Seriously, the point that’s been previously made about the lack of regulation around these companies is bang on.
I honestly can’t see why holidaymakers (and City fans!) can’t use the NHS testing facilities and pay, say, £25-£30 for a PCR test with all monies being re-invested in the NHS. This would knock a lot of these sham firms out of the game straight away (or force them to bring their prices down) and would raise some money for the NHS into the bargain. I get why they might not want leisure travellers clogging up NHS testing sites but the one I went to 3 times between November and January was like the Mary Celeste on every occasion and that was at a time when the pandemic was at its peak in this country.