Ah, guilty until proven innocent... until they run off with your money, they aren't actually doing anything wrong. Yes, you know they are probably a scam but you have no proof of anything. They're being a nuisance.
If they are being persistent, perhaps just contact the police
https://www.met.police.uk/ro/report/asb/asb-v3/report-antisocial-behaviour/
🤷♀️