How to get a credit expedited

I was going to move so I scheduled a move for my internet with ATT. ATT messed it up and moved my service 2 weeks too early. I went round and round with them, never getting it fixed, so I canceled my service with them. Now I see they charged me $99 for an installation fee, when I never got anything installed. I called today and was told they will issue a refund of the $99 (we'll see if they do it correctly - I am doubting it). Anyway, I'm told it'll take 30-45 days for ATT to mail me a check (they won't put it back on my credit card). I asked to have them expedite it since this was all their fault and I shouldn't have to wait that long. The rep said it's a system thing, and too bad.

There has to be a process to get an expedited payment sent to me since it was an error on their end (luckily I just happened to check my account, otherwise it would have gone unnoticed and ATT would have an extra $99 from me - I wonder how many clients never notice?)