Product: Credit card or prepaid card

A few months ago I noticed a charge on my Citibank statement from almost 1 year ago ( Due to personal health issues and 3 deaths in the family which required I travel outside of the country, I did not see the charge until XX/XX/XXXX XXXX, in the amount of {$8800.00} charged in XX/XX/XXXX at XXXX XXXX ( Merchant ). I immediately notified Citibank in XX/XX/XXXX and spoke with the Security Department to file a fraudulent charge. I spent 4 months ( XXXX - present ) speaking with Citi staff, Supervisors and leaving multiple messages for the lead investigator who happens to be overseas and does not have a phone number or access to telephone communications. I have sent multiple emails to the investigator, no response. My only contact has been with Citibank staff and Supervisors. I and my authorized user at the time, did not authorize any charges. In my initial phone call with Citibank, I was informed that a physical credit card was not used/swiped at the location and that the purchase was made online. My authorized user did make a purchase of {$1200.00} around the same time at the Merchant and perhaps that is how they obtained the card number. In doing some research, I found out that the Merchant is my ex-husband 's brother in law XXXX XXXX XXXX - owner of XXXX XXXX XXXX. I have not been successful in reaching him to find out what the charge is for and who made it. After 3 months of back and forth phone calls with Citibank and my full cooperation, I was told that Citibank did not have enough information, therefore, they will be ruling in favor of the Merchant and charging me for {$8800.00}. I tried to obtain a Police Report from local authorities but since I know of the Merchant, I was told this was a civil matter. I explained to Citibank that I am unable to obtain a Police Report in my City/State. Citibank claims they do not enough information so they ruled against their client of 15+ years. I have never had issues with Citibank until now. Citibank supervisor I spoke with for months XXXX XXXX - Texas branch ) said she attempted to call the Merchant and request a copy of the receipt. I was later told, no receipt was provided. XXXX advised me that she spoke with a lady named XXXX XXXX ( Who is not the Merchant but the Merchant 's spouse ). Below are some of the questions Citibank asked XXXX XXXX and the responses ( Please note, the following can be verified via recorded phone calls and transcripts that Cititbank retains ) : Citibank : What is the charge for? 
Merchant 's Spouse : No response provided Citibank : Who authorized the charge : Merchant 's Spouse : XXXX XXXX ( Me ), she came into the office in person. 
Citibank : Are there any records of this transaction : Merchant 's Spouse : No, we discard our records within 5 months. 
Citibank : How was this undisclosed item received/obtained by XXXX XXXX? 
Merchant 's Spouse : It was shipped to her. 
Citibank : Can you provide proof of shipment/label? 
Merchant 's Spouse : No response provided. 
Citibank attempted to reach the Merchant 's Spouse on 3 other occasions to get evidence of said purchase and were told by the Merchant 's Spouse that she will file a harassment case against Citibank if they don't stop harassing her. 
I followed up with the Supervisor a few days later to find out what is the status of my case and I was told that they can not credit my account for the {$8800.00} because they don't have enough information and this may be a civil case. I am not asking Citibank to interfere and resolve a civil matter. The facts are these : I nor my authorized user have NEVER walked foot into this Merchant 's location, never authorized a charge in the amount of {$8800.00}, never received any goods/services, and till this day, Citibank and myself do not have the slightest clue as to what was purchased. This supposed item was shipped to me according to a statement made by the Merchant 's Spouse. Citibank has failed in their investigation. Citibank should have requested proof of delivery/shipment. No physical credit card was used for this transaction. There is no proof that I or my authorized user charged {$8800.00}. The Merchant doesn't even have an online website! I'm not sure how an online transaction was even authorized in this case. Citibank is claiming two things : First, not enough information to rule in my favor ( Which is absurd - not enough evidence should not get you stuck with a fraudulent charge ) ; Secondly, since I know of the Merchant XXXX XXXX XXXX XXXX, Citibank is claiming it's a family/civil matter. Merchant is my ex brother in law who I was not aware had this business until recently nor was I aware he obtained my credit card number. I requested to appeal the decision and was told that Citibank does not have an appeal process in place. I have spent 4 months and endless hours on the phone, cooperating and providing everything I can. I have offered to send an Affidavit to confirm that I and/or my authorized user are unaware of this charge and Citibank has refused. Citibank has been completely unreasonable. I was told I should have Billing Disputes evaluate the claim. On XX/XX/XXXX, I sent a certified letter to Billing Disputes. On or about XX/XX/XXXX, I received a letter from Billing Disputes requesting more information. I provided a long letter explaining what had transpired. On XX/XX/XXXX, I received a follow up letter from Billing Disputes stating that the Security team has already made a ruling on my case and that it is final. In what world does a client have to be stuck paying an enormous amount ( {$8800.00} ) for  something that I am not responsible for. No receipt, no shipping label, no description of item/good ( s ) purchased has been provided by the Merchant. Yet Citibank still believes I should be held responsible for an unauthorized fraudulent charge.