AppleTO
macrumors 68000
I know this is kind of obvious, but it's not your credit card by any chance is it? You could always mark your card as missing/stolen and have a new one issued with a new number.Orders are declined.
If some orders get through, they are cancelled at the preparing to ship stage.
Many years back, one of my credit cards was blacklisted by ebay/PayPal. No idea why, I never had any issues or anything like that. A new card solved that.