Hi. What a sad, sad story! I actually bought my girl at Petco, and I've visited several in the area since. Luckily, all of the stores had fresh water and pellets and the chins seemed healthy. Last weekend I went in to see some, and asked to hold one, and the lady said that I could ONLY if I was serious about buying one. Since I wasn't, she wouldn't let me. So, it's not the whole corporation that's bad.
I suggest, first, ask to speak with the district manager and inform them of how animals are being treated. Go as high up the management chain until you get a good response, and feel that something will be done.
Second, if it comes to it, you could always threaten to picket the store with a few friends, saying how bad they are on like a Saturday, when a lot of people are shopping. If that doesn't work, write a letter to your local newspapers, they always love a good story. You could also call your local news station, tell them they should investigate it.
Well, those are just a few suggestions from Rhode Island. I commend you on your commitment to the proper treatment of animals, and my heart goes out to those poor chinnies.
Good luck and let us know!!