Threads like this one are what make Flyertalk great. I've always turned my nose up at autopay for credit cards (I do it for my fixed-amount bills, though) since the amount varies. I don't know what rock I was living under, but I legitimately had no idea the payment doesn't happen if you've already made a payment on your own, and the autopay T&C for my cards generally say exactly that (although one of my card issuers had T&C was silent on it). I only wish this had come about two months ago, because I was just recently in OP's boat. I forfeited some Hilton points, but not enough to make the reinstatement fee worth it, but it could've easily been avoided without any catch that I can see. Thanks everyone.