You may try writing to the hotel directly, as I did, and make a polite inquiry about what type of hhonors benefits you can expect to receive as a Gold or Diamond or whatever the case may be. Assuming they reply in a timely fashion and tell you you'll get breakfast, as they did to me, then you can print out their reply and take it with you. When the receptionist tells you "no breakfast" you can say that you have written confirmation that says otherwise. It was a pain in the butt, but it worked for me. Hope it works for you.

Hilton, if you are reading this, WE HATE to have to argue with front desk staff for benefits we're SUPPOSED to receive.