Unfortunately the CAA is a rubber-toothed poodle when it comes to investigating, let alone prosecuting illegal ops, even when the prepetrators are AOC operators who already have Flight Ops Inspections and are thus readily investigable.
I personally know of one UK AOC holder that was chartering a King Air on a private C of A in Africa while advertising it as fully UK licenced and insured and their crew included a third 'ghost' pilot whose name was logged for all the (great many) hours over the legal maxima. One of their pilots was renowned for performing aerobatics to wow his female passengers. Indeed he was almost famous for it in the community they worked for.
This was reported but the CAA decided it was 'too difficult and too far away to investigate'.
I also had dealings with a UK scheduled airline that didn't allow Captains to write defects in tbe tech log, instead these were listed on the back of your met paperwork and left for the next guy to read, 3 pages of them on some of the fleet. Not one of the fleet of 5-6 aircraft was fit to fly in airways or in IMC due to defective deicing or radar and on some aircraft both. This could have been proven with 10 minutes work by a Flt Ops Inspector, but when reported nothing whatsoever was done despite their admitting it wasn't the first report of such chicanery they'd had filed. 10 years later I was still hearing of exactly the same going on in that company from its ex pilots. They even managed to have a wheels up landing with pax on a scheduled flight and never filed an accident report. And the CAA never did a thing despite that being reported too!
Good luck hoping they'll do anything to stop illegal charters by PPLs or on the N reg. Pigs will fly first.