I say call the media. You'll get lots of attention and support there. Trust me, I've done it!

Also, talk with the manager. If you're not happy with his attitude, call the corporate office and ask to talk to the head man. Do whatever you have to do to get these cats trapped and taken care of. This is not the cats fault!!! It's human's faults for not being responsible pet owners, damn it! When are people going to realize that anyway???