Product: Credit card

I have a Banana Republic Credit Card issued through Synchrony Bank. In XXXX I set up an automatic online payment from my bank account. This is my usual form of payment and I had no reason to believe there would be an issue. I chose to pay from my current bank account, XXXX XXXX XXXX XXXX, though a debit card associated with this account. The payment I chose to pay would 've covered the entire balance of the credit card for that billing statement ; {$100.00}. On XX/XX/XXXX my payment was processed however it was drawn from a previous bank account of mine ( XXXX XXXX ). In XX/XX/XXXX I used that account for payment to this credit card, but since that time I have closed the account. Naturally, the payment was returned since the bank account is no longer in existence. On the same day, the same payment was processed through the proper account at XXXX XXXX XXXX XXXX. At this point, all should 've been well. Yes, there was a return payment from an invalid bank account, but there was also a valid payment made. However, lines got crossed and I was contacted by Synchrony and advised that my payment was returned and that I still owed {$100.00} to payoff my account. So, I promptly made a telephone payment with the Synchrony bank rep who advised me of the missing payment. I made this payment from XXXX XXXX Bank. This is where I made an error and should not have believed the Synchrony Bank representative without first checking my own bank account. Upon review of my bank account I realized I had been charged XXXX for the {$100.00} from the XXXX XXXX Account and that I was only credited once on the Banana Republic credit card. The fiasco then started. As I tried to explain this story over and over again with Synchrony Bank I experienced pushed back and lack of understanding from nearly every person I spoke with. I spend an hour on hold with several telephone represntativs and made multiple attempts at online chat sessions. I was finally advised that with my own time and money I would need to fax proof of the duplicate payments from my personal bank account. I immediately complied, and faxed the requested documents. I then followed up 3 days later and was advised all was being processed and that it should be resolve in an additional 4 days. When 7 days elapsed I telephoned Synchrony Bank again. This time I spent another hour on hold and with multiple representatives re-telling the story. After some commitment I was then routed to a supervisor who understood my situation but then the telephone line lost connection. Ultimately, after some attempts and an additional half an our I was finally put back in touch with this representative who claims that she has taken care of the situation. While she has refunded the late fee and interest fee I still am not receiving credit for the duplicate payment {$100.00}. It has been over 30 days since I first contacted and I 'm becoming very frustrated. Additionally, I received notification from Synchrony Bank in the form of a letter, stating that my credit with them has been suspended due to my erroneous payments! I fear this situation may be affecting my excellent credit rating and it was truly not my fault. I have spend several hours of time and resources to rectify this situation and I still find it to be unresolved. I am hopeful that some investigation from CFPB will help to conclude this issue and bring me back to whole. Thank you.