Your AT&T story reminds me of my own bad experiences with that carrier. I've been on a pre-paid carrier for a long time now and find I much prefer it.
My bill is completely predictable, and best of all, my phone company doesn't have access to any of my billing information. They can't just decide to charge me a mystery fee, or otherwise screw up the billing.
It's great and I will never go back to post-paid and contracts.