I got this back sometime between then and now:
Thanks for contacting us at Amazon.com.
I am sorry to hear about the problem you experienced with your orders.
If the items is of no use to you, please return it and we will refund
you in full for the item, including associated shipping costs. Also,
as this return is a result of our error, we will pay the return
If you haven't done so already, please note that you can print a
postage-paid return mailing label from this URL:
We will notify you via e-mail of your refund once we have received
and processed the returned items. You can expect a refund in the
same form of payment originally used for purchase within 3 to 5
business days of our receiving your return.
(Snipped the rest as it's not necessary.)
Easy as that. They'll fully refund everything including shipping (not that I pay shipping as a Prime member) and they'll even give me a paid shipping form to send them back for free. And that, my friends, is one of the many reasons why places like Amazon will keep me as a loyal customer and other places can kiss my ass.