So, one property doesn't conform, and you are taking your business elsewhere? Of course, you have that right as a customer, but I suspect you will not find any brand with 100% consistency, whether hotel or airline. Some properties do not conform, and that is easy to confirm here - check out the Trip Reports and Reviews to see which ones do, which do not.

Perhaps a more effective course of action, for Hilton and for you, might be to send an e-mail to Diamond and let them know of your disappointment with the property's lack of customer service orientation and discourtesy, with a cc: to the General Manager (you may be able to find the name in this Forum, using a Search.) Then, take your business elsewhere, since there is no lack of Hilton properties around DFW airport - or pay more to get what you actually want in any case. Nowhere in the Hilton Terms and Conditions does it say you will be upgraded to a suite if you book a two- queen room, and upgrades only occur if the inventory is available and the property is so disposed (particularly to a suite.)

OTOH, one less Diamond is just fine with me.