Have you contacted the hotel directly to ask them? That would be my first step.
Also, if you're there for a major trade show, is there a chance they're 100% booked, although presumably Plat override would come into play (unless it's a citywide event, in which all bets are off).
If you've got a confirmation, trade show or not I'd expect them to make the alternate arrangement, not leave you to fend for yourself.
Cheers.