I have had the same problem. AA said that it can take up to a week for a receipt to post (which seems ridiculous).
I was on US Airways metal if that make any difference. All I have been able to do is send an email to AA and get a canned response about how they are sorry that I am not happy.
Honestly, tomorrow marks my 7 day wait. I'll probably send AA another email to let them know that if they can't send me a receipt that I will be disputing the charges.