Product: Credit card or prepaid card

On XX/XX/XXXX, a fraudulent charge of {$800.00} was placed on my Best Buy Citibank credit card by a merchant in XXXX, Texas. I contacted Citibank to file a claim regarding the fraudulent charge, and they informed me that they were investigating the charge and they sent me a letter stating that I would not be liable for the {$800.00} or any related fees or charges ( see attached documents ). I closed the credit card account on XX/XX/XXXX due to the risk of fraud, and planned on paying off the remainder of the balance before the expiration date of the card ending in XXXX. That expiration date was XX/XX/XXXX. Citibank send another credit card to me in an attempt to get me to continue services with them, this card ending in XXXX, however I never activated the card. On XX/XX/XXXX I went online to the Best Buy Citibank website that I have always used to make a {$1000.00} payment towards the balance. At that time, I was able to see my current balance on the closed account, as well as all account activity and statements. On XX/XX/XXXX I logged back on to the Best Buy Citibank site to make another payment and saw under the account activity that the same merchant in XXXX, Texas had made another charge of {$800.00} to my closed credit card account on XX/XX/XXXX. I immediately contacted Citibank 's Security Department to file another fraud complaint. I inquired as to how someone could place a charge on a closed account that even I could not make charges to. They had no answer. Two days later I went back online to view my balance and see if the charges had been removed, but now the site would no longer give me viewable access to my account activity ( XX/XX/XXXX ), only my current balance of {$1600.00}. This showed that they had not removed the fraudulent charge, but had removed my ability to view my account activity so I could no longer see what was going on with my financial responsibilities or liabilities. I attempted to call them again and get answers for why this was happening, but was transferred back and forth between departments 6 times. On XX/XX/XXXX I logged on to the website to discover that I could no longer see my account balance ; it stated the balance was {$0.00} ( see attached document ). I called Citibank to ask what was going on and spent 3 hours on the phone, getting bounced around between departments, being told by each person that they didn't know what was going on or they didn't have the authority to do anything. Finally I learned that the Security Department created a new account number - without my permission- and transferred the balance over to that new account. The customer service person said that they could not give me access to the new account, so I could not see what the balance was, the account activity, or get a statement. I was totally blocked from seeing my financial responsibilities and liabilities. All she did was send me a generic email giving me my current balance of {$1600.00}, which reflects the fact that they did not remove the duplicate fraud charge to my account ( see attached email ). Now I can not see if someone if putting false charges on my account, I can not see what I owe, and I can not see whether or not they are taking off the fraudulent charge. Citibank has been trying to dodge their culpability and responsibility in these matters, and is now trying to block me from having access to my own account while a fraud investigation is pending, causing serious financial liability issues for me. They have been uncooperative, deceptive, and they changed my account number without my permission, blocking my access.