I had a run of missing stays earlier this year. I tried the fax route once, and nothing ever showed up, so I called Salt Lake directly. While I was on the phone with them, they called the hotel and verified the stay, and the points posted the next day. That's the route I've taken from then on, and they've gotten a lot better in keeping up.

I think the fact that I'm Platinum helped, but the direct call seems to be the most effective route.