I suppose the excuse they are trying is - customer told us it was a corporate card. But that ignores the form being broken and defaulting back to that selection even after the customer changed it to personal card.

Surely they have some link with Amex where they don’t need to ask the customer what card it it? Because if they are relying on corporate customers to self select and pay, what’s stopping them ‘accidentally’ choosing the personal card option and avoiding the fee?

Seems a poorly designed system whichever way you look at it.