AT&T is a case study in how not to treat your customers.
AT&T has made it abundantly clear that they don't care at all. The latest proof of this comes from this thread in AT&T's customer forums.
To recap, a paying customer posts a complaint about their service, and an AT&T employee replies telling them to return their phone and go away.
Mark my words, it's this kind of attitude that is going to be why AT&T is going to be transformed from a large company into a small one.