Product: Credit card or prepaid card

I pay my credit card balance in full every month, well before the due date, and I pay by check sent via the US mail. We opened a new account with American Express ( XXXX XXXX XXXX XXXX ) after being with XXXX for decades, hoping to start earning XXXX XXXX XXXX XXXX for travel. I never had to pay interest or fees with XXXX because I always paid the balance in full every month and in plenty of time to meet the due date, and if there was ever an issue with their records showing the payment did not get processed until a day or two after the due date, XXXX admitted that it was probably an issue on their end and that they would always honor the customer 's payment as " on time ''. Most credit card companies monthly invoices are not received via US mail until 2 weeks before they are due, so they are 80 % of the problem to begin with. I paid my Statement with Closing Date of XX/XX/XXXX balance of {$7400.00} well in advance of the due date of XX/XX/XXXX, and American Express claimed without any proof that they received it on XX/XX/XXXX. They assessed me with {$150.00} of interest and {$29.00} of fees. After numerous calls to talk rationally with them and to request proof that they received the payment in full late by 2 days, they would only waive the {$29.00} in fees, but they said that they are unable to provide any proof that the payment was received 2 days late. We believe that the American Express internal operations was responsible for not processing our payment in a timely fashion, and that our payment was in fact received on or before XX/XX/XXXX - the due date. On the Statement with Closing Date of XX/XX/XXXX, American Express charged another {$110.00} in interest that they said was also related to the XX/XX/XXXX statement balance they they claim was received on XX/XX/XXXX. We called American Express five times to discuss this matter with them and we were treated very disrespectfully and in a condescending manner. We told them that we would paid off the balance of the credit card in XX/XX/XXXX and then cancelled the credit card. We just received the Statement with Closing Date of XX/XX/XXXX and they assessed an additional {$4.00} in interest and {$29.00} in fees because we have not ( and will not ) pay the previous {$260.00} in improper interest charges assessed to our account that is the fault of American Express, not ours. So the balance that they claim that we owe is {$300.00}, which is not supported by any evidence that we paid the XX/XX/XXXX invoice two days late. This is a completely fraudulent assessment of interest and fees that is not based on any evidence that American Express can provide. We tried unsuccessfully to have the XXXX XXXX XXXX resolve this matter, but American Express would not cooperate with the XXXX XXXX XXXX and just sent us a letter stating that they would not remove the interest charges because " we are unable to issue credits for interest charges ''. Then we tried filing a claim with the CFPB and American Express called my phone once and left a message with a number to call back. I tried calling the number for two weeks straight and left voicemail messages, and the person would not answer the phone nor return my call. Then American Express told you, the CFPB that an unauthorized person was listed on the complaint, which would be my husband and who also was a listed cardholder. So we are now filing a new complain and it will not include my husbands information so that American Express can not use phony excuses to avoid dealing with their fraudulent assessment of interest and fees on an account that was paid in full and on time each month we had it open. Claiming that interest charges can not be reversed is a complete lie and constitutes collection harassment by American Express. If American Express is unable to issue credits for improper interest charges and then bullies customers ( and ex-customers ) into trying to collect them, then the Federal government agencies overseeing fraudulent charges and improper collection techniques should investigate American Express for a massive fraud scheme, much in the same way the XXXX XXXX was found guilty of fraudulent business practices and fined {$1.00} XXXX. I presume that this issue is widespread within American Express and that they are collecting millions and millions of dollars each month in improperly assessed interest and fees, which seems to be a fraudulent business practice of significant magnitude.