Amazon Marketplace is less crap
After my venting yesterday I received an email from an Amazon employee who reads Planet Debian, and he pointed me at http://www.amazon.com/gp/help/customer/display.html?nodeId=537868, which covers how to make a claim.
I've no idea how one is supposed to directly find that page, as it didn't jump out at me when I went looking.
I've filed a claim, we'll see what happens...