Complaint sub-issue: Credit card company isn't resolving a dispute about a purchase on your statement

I initiated a dispute with Citicards/Citibank concerning an unauthorized charge made on XX/XX/XXXX by a merchant we are working with for new hurricane impact-rated sliding glass doors and windows, XXXX XXXX and Doors. The Dispute no. with Citibank is XXXX. The amount of the disputed charge is {$24000.00}, and it would have been the second of XXXX payments to be made under the contract. The dispute was initiated in XX/XX/XXXX, and I provided the contract and numerous communications with the XXXX establishing that it was not entitled to make the second charge on our credit card until all merchandise had been delivered. Some, but not all products had not been received by XX/XX/XXXX, and still have not been received as of today 's date. Citibank initially credited my account for this charge but quickly reversed that credit and reinstated the charge saying that we had not provided sufficient information to sustain the chargeback. But Citibank admitted that it had no signed charge authorization in its files, and that the XXXX had not completed an XXXX charge. Citibank has refused to provide us any information that it was receiving from the XXXX throughout this process, although it is apparent that it is providing the XXXX with the information we submit to Citibank. Citibank has ignored that there is no signed authorization from us on this charge, and has directed in a XX/XX/XXXX letter that we undertake an extensive process to obtain information about the value of the non-delivered or incorrect products delivered from a " comparable merchant. '' Since this is a nearly {$70000.00} contract, the work required of an uninvolved " comparable '' merchant would be extensive and we could not find a merchant to do that, so I spoke with Citibank and we were instructed to hire an expert that could provide the data needed to Citibank, including verification of nondelivery, the cost of the nondelivered items, the cost to remove and reinstall the items that had been incorrectly installed ( all of the sliding glass doors and window that had been delivered were installed incorrectly and rejected by the local XXXX  Department ). We provided the requested information by hiring an expert glazing consultant at substantial expense and undertaking a complete inspection of the products and work. That report was delivered to Citibank on XX/XX/XXXX, supplemented on XX/XX/XXXX with cost information. The costs of the products that were not delivered exceeds {$22000.00} without consideration of the costs to remove and reinstall the products. Citibank has written us after the report and stated we never responded to their XX/XX/XXXX letter, which is false. Citibank has refused to reasonably investigate and evaluate the substantial information submitted. We have submitted to Citibank numerous reports from the XXXX  Department that all of the installation work has failed inspections for Code compliance and that a STOP WORK order was issued by the XXXX Department on XX/XX/XXXX due to the Merchant 's improper work. We have now been informed by the XXXX, over 6 months after the dispute started, that it claims to have an " XXXX '' signature, though it has never provided it to Citibank or us until XX/XX/XXXX. That " XXXX '' signature is an obvious forgery - a straight line through a signature block on a form where the number of our credit card was manually keyed-in. Citibank has admitted the signature is " suspect '' but continues to charge our credit card. We have communicated with Citibank numerous times by facs, by voice on the phone, and by email, and have not been able to speak with a person who is familiar with our file. Each time we get a new low-level representative in their Dispute XXXX Department XXXX We need assistance, please. We have a substantial file if more information is needed. Thank you.