Complete assclown behavior throughout. It would be one thing if this had been going for for a month or two, maybe a quarter or two… but ten years?! They’re clearly fucking you over out of either malice and/or incompetence, and by allowing it to go on, you’re politely enabling them to do this bad behavior to someone else’s business.
If you feed stray dogs, you end up with a neighborhood full of dogshit everywhere you step. Bill them; if they don’t pay, talk to an attorney.