As Elysium pointed out there are state laws about tenants stuff. I used to work for a guy that managed a ton of properties and in our state you actually aren't allowed to give away, sell, anything other people's stuff if they leave it. He has a HUGE warehouse space filled to the brim with people's stuff and he's obligated by law to keep it all.

Not to be a downer at all, because i think it sucks that they are taking advantage of you like this, but please check your laws, it would stink to get a notice one day that you have to pay for the replacement of his stuff. Good luck.