Just go into an AT&T store and ask. If you can't get anywhere, ask for the store manager.
Last try - call them and ask for "retention". They can jump the gun by a week or so if they really want to keep you as a customer. I've gotten about 4 "updates" in service without asking for it. (The more people you know, the better the chance that you'll get something that doesn't cost them anything. Minutes are free - the equipment is there, whether it's being used or not.)