I really hope you don't let this go without a fight. I think the "participating" thing is a red herring; I would be extremely surprised if your hotel was on a non-participating list, assuming you aren't in Timbuktu or some such. Get the GM in a room with a phone, call the gift card line, as for a senior supervisor, and get it straightened out. I guarantee you the gift card customer service management isn't going to want to let this go any more than you do. Tell the GM you plan to post on every travel site you can find, and follow through.

Later on, when you catch your breath, go back to them (GC) and insist on a free night, or some other compensation, for the first hotel refusing the card. IMO this whole fiasco started with failure to deliver the real gift card (same thing happened to me, and I just cancelled it, BTW).

Normally I am not one to throw a hand grenade when a simple mistake is made, but you have suffered a real loss of time and financial hardship, not to mention having to scrimp on food, and it's because the GC folks aren't getting the word out.

Doubt you can get around the pre-authorization problem, but the failure to accept the card is unsat. Have the GC folks figure out how to charge the card, deduct it from your balance, and refund your CC - anything else is unacceptable. Fight!! and report back!