Ask your bank how you can block someone from sending you money. Bet you a quid that you can't.

With Monzo you can 🙂 You can either ask to block internal P2P stuff (which would be split the bill requests, payments to Monzo contacts, joint account creation requests), or you can ask to block abusive FPS payments (by account number and sort code). I actually recall when this was made a couple of years ago, and I used to be one of the people that modified the config to action these block requests (it's now more sophisticated).