TPS does sod all. I still get UK based calls. ATM 4-5 home improvement or green initiative calls per day, some are automated. 10+ non UK calls a day from far distant lands, where everyone has a false Anglo-Saxon name, that would like to ask me a few questions.
All TPS does is ask legit companies to not phone those numbers on the list. Nothing to stop unscrupulous ones from doing so. There’s nothing OFCOM can do if you don’t have a number, most are withheld, or the company name, and none of them will give you that if you ask.
I could block all withheld numbers on my mobile, but I do get quite a few legit calls from unknown numbers, that’s the way some companies phone systems, especially Internet based phone systems, work.