Amex Prepaid Card Complaint

Amex Prepaid card department,

Gift or merchant card Unauthorized transactions/trans. issues Nevada

My card, PIN, and ID was compromised. I 've told Amex this several times and they 're telling me they the charges are valid and I can not contest to it further. They also shut down my account that 's been opened with them for a while. These are the only fraudulent transactions I 've ever encountered on this card and they 're refusing to reimburse me, they also refused to give me documentation as to why my claim was denied. They wo n't even tell me why the transactions are valid over the phone. They did n't even file the dispute correctly, they owe me more than $740.00. That 's the total they 're claiming that I filed for. I can not get thru to them or do anything about this!!!