My hometown Hilton once attempted to turn down a Senator for the per diem rate. Luckily it was one of the Senator's staffers checking in before the Senator arrived, and I was able to call the GM and get things straightened out before they pis**d off a sitting Senator, but it goes to show you they'll try the old bait & switch on anyone.

I've never had it happen to me, but I'd definitely call the Diamond folks and let them know what their property is doing...