Amazon already said from memory that exiting orders would be charged via the original payment method regardless of shipping date.The argument I would make is I have not removed my payments under the terms I signed up to, but instead Amazon are choosing to not accept the payments. It is one thing to stop accepting a method of payment for future payments but another to change it during a financial contract.
I dont think I have ever had a credit financial product where method of payment has been changed during its length of contract even if the company changes things for new products.
It was only new orders that would not be accepted via visa credit.
Basically if you'd placed an order up to the 18th for something and it was accepted with a visa credit card, they would charge that card even if it didn't ship until December. It's the only way they could do it given how many people have pre-orders for things and how long the pre-order window can be (with DVD's it's often 2-3 months, with books it can be a year, and the longest I've personally had was nearly 2 years as a DVD kept getting pushed back).