Product: Credit card

On XX/XX/XXXX me and my wife did a balance transfer using our citi credit card for {$15000.00}. Citi charged us an extra {$600.00} for doing the transfer so now we owe citi {$15000.00} but they were going to pay {$15000.00} in my XXXX XXXX card. We waited past the 10 business days they advised and still saw that XXXX credit card was not paid by Citi bank. I called and they informed me I needed to wait more so I did. Few weeks passed and still nothing. I called and same thing, was informed to wait a little longer. Waited months now and still nothing, so at this time I know owe citi bank {$15000.00} and my XXXX credit card {$15000.00} and paying interest on both. I was calling both credit card companies trying to find out what happened to the {$15000.00}. XXXX credit card advised me they never received any payment from citi for {$15000.00}. They informed me to call back and ask them for the transmission details which is proof of the transfer. I called Citi again and asked to speak to a supervisor, I explained the situation and they looked into it, they even confirmed that it was sent to the correct credit card. I kept asking for any sort of proof that the transfer was done, I asked for the transmission details since that is what XXXX credit card told me to ask for and have them fax it to XXXX. The supervisor informed me that they will take care of that and send the requested information to my XXXX credit card and to my house. We never received any proof that balance transfer was made. Months passed and now its XX/XX/XXXX, we called XXXX to verify if they received the transmission details, they advised no. I told XXXX credit card the situation which they advised to three way the call with them and Citi bank credit card to get to the bottom of this. I did, when on the phone we requested to speak to supervisor again, we then spoke with Citi supervisor XXXX. Who looked into the situation. I told them that I have XXXX credit card on the line with me and they are requesting proof, the transmission details that the balance transfer was made because they never received payment. They informed me that I need to hang up on XXXX or else they wont give me the transmission details. I hanged up with XXXX but they still did not provide me with the transmission details, they have failed to provide any proof that they sent {$15000.00} to XXXX XXXX card. She kept us on hold for a long time then gets back saying she found the problem, that 4 digits were wrong on the card I was transferring to. I found that to be false because when I did the transfer I checked multiple times on the card information since this was a very large transfer. I understand maybe 1 number can be wrong if a mistake was made but she advised 4 numbers which that is a lie. It feels like she made that up to have us hang up because she solved the issues. But we went with it and said that the transfer will soon go through. I called again on XX/XX/XXXX to find out whats the status, spoke with Citi card again and they gave us a different answer, that They are looking into what happened to the transfer which I was confused because XXXX XXXX supposedly had figured it out and fixed the issue. It is now XX/XX/XXXX, 3 months after I made the balance transfer and I still owe 2 credit cards {$15000.00} plus INTEREST! I called over 5 times and nothing has been done. Citi has not provided any proof that they did the balance transfer but keeps insisting they paid XXXX XXXX card.