Aside from the Reno quasi-Hilton, I've only had a couple of instances of not-so-pleasant check-in staff - and dozens of of them who've been excellent.

I've never been a Diamond, but isn't that what the Diamond Desk is for - to over-ride room availability if possible? He should have contacted them prior to showing up. That clerk deserves one of those "You've Been Caught" forms for dealing with this fool so nicely (offering to book elsewhere).

Welcome Provisoir - please post often!