Was going to say exactly that. You could also try one of those roller stamps that helps block out information on paperwork (invest in a good one). If you financially can’t afford either option collect all your personal rubbish (eg paperwork) and take it to office works they do 500 pages for $5. Start mixing yucky food waste across all your rubbish to make this process disgusting for them to do.

But if you feel unsafe (for what ever reason) seek advice from the police. If you feel they may ever attempt to enter your property try and get some security cameras. This behaviour is concerning. Unfortunately you can’t control them so hopefully these ideas can make it harder or less appealing for them