Amex Prepaid Card Complaint

Amex Prepaid card department,

General purpose card Managing, opening, or closing account California

Amex Serve has a policy of holding a consumers funds 7 days after a transaction is cancelled. They claim to not have the ability to release the funds even if you submit proof from the merchant that the transaction has indeed been cancelled. I submitted a complaint within the last 3-4 weeks and received a vaguely worded response that in no way addressed my concerns. While I 'm quite sure this practice is not illegal, it is a great inconvenience to the consumer.