Waiting for refund but AT&T has an error on their end.

I'm not going to waste time and provide as detailed a description as I just typed for an hour and vanished because the site stated it had a "hiccup" when I tried to post earlier!  Here is the gist of it:  My account is supposedly delinquent at approximately $400.  I was actually supposed to receive a prorated refund after paying what I thought was my last bill.  After numerous wasted time on phone calls to multiple reps. spanning months of time, I have been told over and over that there is an error on AT&T's end about my account.  I first called on March 9th to cancel my home phone and DSL.  All the reps. state that their notes show that the request was entered into the system on March 10th.  My phone and DSL are, indeed, non-functional, but guess what, I keep receiving a bill, I have no refund, my account is considered delinquent, and my email accounts are locked out.  Calling obviously doesn't do anything even when the reps. say it is AT&T's problem and I am due a refund.  There is no way to directly email AT&T.  I had been with AT&T for about twenty years.  There seems to be no reward for loyalty.  I suppose since I tried to cancel my services, I am no longer valuable to them and, thus, not worth helping.  One of the reps. actually had the nerve to ask if I would like to sign up for cell service with them!  Sheesh!  There has to be a way to get this resolved.  I want my emails back although I have already forwarded emails to another email account.  I have had the AT&T emails for almost twenty years.  Does anyone know how I can get this fixed?