Product: Credit card or prepaid card

In XX/XX/2019 my company made two car rental reservations in order for me to travel and perform my job. Both reservations were paid for with a corporate prepaid voucher. In order for me to pick up the cars I had to have a valid credit card on file in case of accidents and/or damages made to the vehicle. At the completion of both rental periods, both vehicles were returned with no damages and my company received a final receipt reflecting a zero balance. However, both car rentals were fraudulently charged to my card. My credit card is a secured card issued by CitiBank and only had a limit Of {$500.00}. I opened this card in XXXX in an effort to build/establish my credit since I have virtually none. Since these transaction were allowed on my account, I have been unable to use my card and therefore my credit has suffered. I filed two disputes with CitiBank and sent copies of the final billing invoices received from my employer reflecting a balance of {$0.00}. Month after month I have battled with CitiBank over these transactions. The Investigators have claimed to have not received the documents or the at they were blurry and could not read them. In response I both emailed and faxed on numerous occasions clearly legible versions of both receipts. I have also spoken to at least 7 Supervisors employed at CitiBank who have all notated my accounts in my favor of the corrections to be made and urging the Investigators to reassess the disputes and expedite the process. Each Supervisor assured me that since they were in a Supervisory Position that their respective comments to correct my account would have weight with the Investigators decision to complete the dispute. Each employee that I worked with on this matter all agreed that I was charged in error. I did not encounter any CitiBank employee that made any claim that I was charged correctly. Yet, my account has remained overdrawn in excess of over {$2000.00}. None of the employees offered a valid explanation as to why these transaction were even allowed to clear my account when my credit limit was only {$500.00}. As of last week, my account has been closed and my initial security deposit has been applied to my account. This account reflects this status on my credit reports as well. When I spoke to a representative at CitiBank, they only offered a response of there is nothing more we can do. This is simply ridiculous. I have worked hard and was simply trying to establish credit to better my credit file with the hopes of eventually purchasing a home using my VA Benefits. I do not understand how or why this has happened nor why CitiBank has allowed this to occur without any care whatsoever of the effects it has had on me ... their customer that believed in their false statements of protection against fraudulent and unauthorized transactions. I was even demoted by my employer because I have been unable to travel or obtain clearance to pick up rental cars in order to visit clients without a valid credit card. I have been with my company for over 5 years. Im now forced to start all over again hoping that another opening happens in my old position. This has completely ruined my life. And CitiBank only offers an unsympathetic apology. This is clearly a case of corporate level nepotism as CitiBank failed to offer any protection at all to me as their client. They failed to protect my interest and allowed transaction well above my credit limit to clear my account.