ATT or not ATT?

I have been with t-mobile since 03. It has been adequate for me since I only want to make calls and use the calendar and alarm clock features. It is a plain candy bar type which comes free with a plan. I have been out of contract with them for about 14 months. Recently I have noticed that many of my incoming calls are going straight to voice mail. The phone doesn't ring when the call comes in but shortly after it does then I get a "beep". This is annoying! I took it to t-mobile service reps at a mall kiosk and they didn't seem to know anything (they told me that i should increase the length of the ring tone). I would like to switch to ATT but from what I can gather from the web their service is almost as bad if not worse. I also wanted to shop the internet for free phones along with a plan but I have never done this before and I need to know who on the net is trustworthy. The rebate are pure bull! They promise that you get a free phone and an additional $50 etc. via rebates. I will not buy anything with a rebate unless they are a reputable store that will honor them. Panasonic tried to hose me off for $100 on a fax machine. I never got the rebate. They claimed that all the rebates are handled by a 3rd party dirt bag in south jersey. These people of course denied ever receiving the rebate request. When I went to the store(office max) where I bought the fax they gave me the rebate in cash right there!

Any comments or advice would be welcomed. Thanks in advance.

Several things. First of all, there is very little chance that the people who work at a store really know much beyond what it takes to sell phones and features.
So for help, call T-mo tech support.
As far as the web goes, it is not a good sampling of the people who use the service. The people most likely to post are the people that are angry for some reason, and often times they are blaming ATT for their own problems. I have seen people complain because they knowingly signed up for service, and then decided they wanted to change carriers and do not want to pay the fees.
Does ATT have issues, yes. But then again so do all the carriers, I doubt that ATT is any worse than the others.