Cancelled Zipcar account b/c of multiple customer service fails

I was one of those $50/month customers. Missed an appointment because car would not unlock--customer service tried to unlock it remotely and could not--and there were no other cars available in the lot at that time. The agent I talked to said he was not authorized to credit me any more than that day's reservation plus an hour credit. I wanted to talk to someone about the big picture--what recourse do I have when this kind of thing happens etc. Left a phone message a the Boston office that after two weeks had not been returned. Went in in person...the receptionist, who is apparently also the face of customer service, studied her computer for a while and then told me that "the thing is, the people after you didn't have this problem."...! Which, um, surprised me as a tack. Then she offered to refund _one hour_ of my two hour reservation--in other words, much less than the guy who tried to unlock the car for me had offered. Wow. And finally, even after I had said I was considering closing my account (having alluded to the multiple other times I have had trouble with the system, even while the cars are great), she said, "in Zipcar's defense, they weren't with you when this happened."

As someone who commented lower down on this page wrote, "I can't really know why it happened, but maybe you should pretend to believe your best customers when they have a problem like this."

Now I read that they are readying for an IPO. I wonder if they are working on a plan to deal with the people using their service. B/c in this one minor area, they are incompetent.