I emailed just to make them aware that this happened and the hostile, "PROVE IT" type response I got was so incredible compared to Amazon's facilitation of the customer.Wow. That's entirely the opposite experience I've had.
Twice I've had problems with my Wal-Mart orders. Both times I filled out a form online, and within an hour someone very nice from Texas (both times — I inquired about their accents) called me on the phone to not only apologize, but to replace the item at no charge and refund the price of my original purchase.
Amazon also gives exemplary customer service when things go wrong, but your Wal-Mart experience seems really out of left field.
(I had an entire Easter dinner from Whole Foods sent to someone else's house and Amazon had another delivery at my door in a little over an hour, with a $20 credit. Interestingly, Amazon won't tell you which house an order was accidentally delivered to for privacy reasons, or I just would have knocked on a neighbor's door.)