Complaint sub-issue: Card was charged for something you did not purchase with the card

TO WHOM IT MAY CONCERN : My name is XXXX XXXX. I am hoping filing this complaint through the CFPB will help resolve the disputes Ive previously made with Citi Bank regarding my CitiBusiness Platinum Select World Mastercard ending in XXXX. To specify, I am disputing a {$490.00} charge for XXXX which I did NOT initiate or authorize. As Ive previously told Citi, this credit card was stolen and used to make unauthorized/fraudulent charges between XX/XX/XXXX-XX/XX/XXXX ( dates provided by Citis online statement ) for almost {$3000.00}. I also have a XXXX account which was hacked ( date unknown to me ) and the Citi card was used to make purchases on XXXX which I, in no way whatsoever, ever authorized. I reported this card as stolen to Citi as soon as I found out. Citi was supposed to investigate the charges, but I have not received any substantive investigation results and Citi is now demanding I pay the charges. Nothing Citi provided me showed how these charges could possibly have been made by me. This scenario seems to be a nationwide problem due to all the hacking and poor security measures put in place by those entities which store our information. I have experience in IT and know that Citi could easily figure out where these charges originated by a simple IP check or other various means that would point them in the right direction. Citi has, instead, chosen to try and collect this debt from me. I am assuming because that is easier for them than actually investigating the charges. This is unethical and violates our agreement. I should not be held responsible for charges that I did not initiate. Citis investigation stated ( by no explanation or means of how they reached their decision ) the charges are reversed back to me, even though I did not make them and even though they can not show how I could possibly be responsible. Citi is responsible for the cards activities. Citis own security system should have detected the spending pattern on the card was highly irregular and contacted me at that point. I know this is commonly used by CC companies because I have had to verify purchases which seemed out of place in the past. There were 18-charges within 8-days totalling almost {$3000.00} and Citi didnt contact me once during this time to verify they were legit. This card wasnt a go-to card for me, I typically used it a few times per month ( 3-4 times ) which my account history shows and which should have alerted Citi to possible fraud or at least suspicion of, on their part ( please see XX/XX/XXXX vs. XX/XX/XXXX statements attached ). I am requesting all documentation, such as any signatures that were recorded when the stolen card was used, and any other documentation which Citi used to come to this incorrect decision. I realize investigating charges can be timely, but this is their responsibility and they have the means to do so, and the cost should not come down on me because the bank has deemed it cheaper or not worth to get to the bottom of. I have dealt with the situation as Citi requests when your card is used without your permission : I promptly reported the card stolen as soon as I found out. Citi should have known sooner, but thats neither here nor there, at this point. Thank you for your time and ( I hope ) prompt attention to this issue. If there is anything I have failed to do to meet my burden to Citi, please let me know. I would like to have this resolved as soon as possible. Again, thank you.