Product: Credit card

On XX/XX/year> I initiated a balance transfer from my Citi Bank XXXX XXXX to my XXXX XXXX XXXX card in the amount of {$5600.00}. I used the XXXX credit card app to process this transaction. I kept watching the card transactions in both bank apps to insure the transfer happened. I did in fact see that the balance had been added to my XXXX XXXX card but Citi Bank also still showed the {$5600.00} balance. I contacted XXXX the first time XX/XX/XXXX to inquire about why Citi Bank still showed a balance. The XXXX representative told me everything was fine on their end and it was a Citi Bank issue. I called Citi Bank and their representative told me the payment had never been funded to my account and it was a XXXX XXXX  issue. I once again called XXXX and was told that information was incorrect and to call Citi Bank back again because it was their issue. Citi Bank refused to let me speak to a supervisor and hung up on me. 
On XX/XX/XXXX I called XXXX for a third time. I actually got a very kind representative who finally tried to help. She looked into it and showed the payment had been funded to the wrong Citi Bank account. The third and fourth digit were wrong. She filed a case for me with XXXX. She told me this was a fairly common issue and XXXX would contact Citi Bank to fix the issue and have the funds removed from the incorrect account at which point I would most likely have to reinitiate a new balance transfer once resolved. She informed me this would most likely be resolved within 10-14 days. At this point I had invested over three hours on phone calls trying to get this resolved. 
I patiently waited checking both banking apps every 2-3 days waiting for the transfer to be voided. I checked my email and mail for any updates on the case I had filed. Nothing! On XX/XX/XXXX I contacted XXXX once again to find out what the status was. I was told the case had been closed, nothing was done, and to call Citi Bank again because it is their issue. I called Citi Bank and they said it was absolutely not their problem it is XXXX responsibility to fix. I called XXXX once again. I got a very helpful agent. She told me that she would initiate a three way call to Citi Bank to help and resolve the issue. We called and explained to the representative who we both were and the reason for the call. XXXXXXXX XXXX  agent identified herself as a XXXX XXXX  representative and requested to speak to a Citi Bank supervisor. The representative told her no and refused to allow us to speak to a supervisor at which point she hung up on us. XXXXXXXX XXXX agent was persistent and we called again. This time we asked for a supervisor again. We were told to hold for the supervisor and disconnected intentionally again. We called a third time and XXXX instructed me to tell them that a payment had been made to the incorrect account number and I needed a supervisor. This time a supervisor did come on the phone. He proceeded to look into the information he was given until he was made aware it was an electronic balance transfer. At this point his demeanor changed. He went back to saying nothing could be done on their end, the account funded was not a Citi Bank account, and to call XXXX XXXX. XXXXXXXX XXXX agent then made herself known on the call and informed him it had been funded to a Citi Bank account. We had the full account number. The supervisor then stated there is no such Citi Bank account and XXXX would need to fix the issue. XXXXXXXX XXXX agent reopened the case for further investigation. 
I am currently stuck in a position of now showing I owe double the amount, one of which the balance is not my balance. I also believe I entered the information correctly when I submitted it on the XXXX app and the number was transposed when being submitted to the bank. I do realize I have no proof of that. In hind sight I now know I should never have relied on technology and mailed a paper check so I had proof. Regardless this matter needs to be resolved and I keep hitting brick walls. I have now invested six and a half hours on the phone between the two entities with no resolve. I was also given a fax number to send over documentation to XXXX dispute department. I have attempted to fax the documents 12 times at varies times of the day and not one time has the fax gone through. Always busy! I have documentation of every attempted fax. I also mailed 6 certified letters. If someone can please be of assistance and help in resolving this matter I would greatly appreciate it.