Start with Amex. They have been good when I have had disputed charges. They might have you contact Amazon at that point, but they will probably put the charge on hold while you do so.

Also, change your Amazon account to 2 factor verification required for purchases.

Edit to add: Also, consider setting up notifications on your phone anytime there is activity on your Amex charge card. I have that with American Express and I know immediately anytime I have incurred a credit card charge.