Amex Prepaid Card Complaint

Amex Prepaid card department,

General purpose card Overdraft, savings or rewards features California

Ok there was a charge on my American Express card which was unauthorized - I made the dispute threw my bank and they did not handle it properly they said that the merchant contact them saying that they had already paid me in a form of check I never received any check plus I thought that the money had to be put back into the card oh another the check is not even under the account holder $4800.00