double billed by autopay

I moved a line from PrePay to my Post paid acct.  They kept charging that line on my credit card for 5mos (it was moved to Post Pay and immediately started charging there).  They promised 2xs to refund.  Last phone call - 5hrs & 46mins in length - they are denying the refund because their records show the autopay was suspended.  I have that msg also, but I also have credit card statements to show they continued to charge for another 5mos.  A rep said to submit a claim thru the "Missing Payment Info Form" and I'd get a resolution in 72 hrs.  I filed the claim, complete with all supporting documentation that they kept charging.  It's been a week, and still no resolution.  I've been on hold now for 45mins waiting to speak to someone.

If I don't get resolution now, any suggestions on how to get a refund?  I'm so ticked off about this, my only next step is to file a case against them in Small Claims court.  Total mistake on their end, but I want my $375 back.  Totally unacceptable.