Product: Credit card or prepaid card

This complaint is against Citi Bank, which owns Shop Your Way credit card. 
On XX/XX/XXXX, there was a fraudulent charge of {$1800.00} made by a scammer XXXX party named XXXX aka XXXX XXXX, that purposely misrepresented themself as XXXX XXXX hotel when I made a reservation by phone. As I became frustrated and livid by the incompetence of the many Citi Bank employees whom I spoke to in the XXXX XXXX XXXX for my claim of fraud, in the XXXX XXXX XXXX, and finally in the XXXX XXXX XXXX, I contacted XXXX, and the MERCHANT REFUNDED the {$1800.00} in full to CitiBank, which left my balance at XXXX dollars. I had paid my account balance in full to Citi Bank, with the exception of the disputed amount. 
I have spent from XXXX trying to get my account corrected. I have literally made approximately a dozen, if not more phone calls and spoke to various people in the afore mentioned departments. 
The person whom I last communicated with was XXXX at the XXXX XXXX team. He can be reached at XXXX. After speaking to him in detail about my issue, I received notification on XX/XX/XXXX that read : Please accept this letter as confirmation that we have credited the disputed amount of {$1800.00} to your account ending in XXXX. We have also adjusted interest charges totaling {$2.00} associated with this sale. 
The next time I checked my account, the {$1800.00} was still showing on my account. Therefore, I contacted XXXX again on XX/XX/XXXX. He did not understand why the {$1800.00} balance was still on my account and opened another case so that he could contact both the people from XXXX XXXX and Billing Disputes to work together to get the {$1800.00} off of my account. 
Well, the result of my inquiry was a subsequent letter, dated XX/XX/XXXX, stating : We understand from our phone conversation on XX/XX/XXXX, that you dispute the current balance on your account of {$1800.00}. We have reviewed your claim and determined that you are responsible for this portion of your balance. 
The notice then went into debits and credits that they INTERNALLY computed on my account. If the fraudulent charge was refunded in full to the bank by the merchant, and the BANK erroneously computed the figures on my account, it is THEIR error and it is NOT my responsibility to absorb that error!!!! 
I spoke to XXXX again on XX/XX/XXXX to discuss the XX/XX/XXXX letter and the gist of his answer was that the buck stopped with his department, there was nothing further to discuss, that we were going around in circles, and he was terminating our conversation. 
This XXXX action of Citi Bank is beyond words, and something needs to be done to rectify this situation!! I can not conceive of the bank trying to hold me responsible for money that has already been fully refunded to them by the merchant! 
The stress of this continuous battle with Citibank has caused me severe emotional and physical distress. I suffer from a medical condition that is triggered by stress! I am a XXXX XXXX XXXX federal retiree, and my only income is my federal pension. This only adds salt to the wound. 
I paid the minimum amount due on this fictitious balance to prevent reports to the credit bureaus and negatively affect my XXXX score. 
PLEASE HELP me resolve this issue and get the {$1800.00} balance removed from my account!!! 
Thank you, XXXX XXXX