Another point if it is Hilton. I would highly recommend reaching out to their twitter support. Give them the details of your booking, provide a picture of your confirmation & explain in detail what happened. I would also suggest not asking for any compensation at that time, just state that you are frustrated that you booked & the hotel won't honor the booking. In my experience, they've given me more than what I would even think about asking for.
I've tried calling into the Diamond Desk as well & basically got told their is nothing they can do for various situations. For whatever reason, the twitter support team seems to have way more leeway in helping you out.