Thank you all for your input. I am sorry my original post was not very clearly written and might confuse people.

My husband is the Diamond member and the reservation is booked under his name on Hilton.com. He attends quite a few events per year., Whenever it is master billing, no points will be given but we always get benefit/recognization. Sometimes we were told we would not get the points when master billed but we would get the night credits. In reality, it was not true, we were never given night credit either.

Anyway, my husband talked to another attendee who is also a Diamond member and he was given lounge access. He said he sort of had to argue at check-in to be granted benefits. So I went and talked to the lady at the executive club. She initially told me the same thing my reservation was under group rate so no lounge use is allowed. I further asked her why since we booked on Hilton.com and the bill would settled on our credit card. She did a little more typing and said it was a mistake and we can use the executive lounge.

I do not know how the contract was written. I was just being puzzled that we were denied benefits. In fact, the event provided breakfast and lunch, so lounge access was not a big deal, just want to understand why.

On the sideline, the hotel is fine but I was not too impressed. We ate at their dinner buffet one night, not very good. We went in around 8 pm, most of the food was not replenished since they closed at 9pm. Some looked almost bare. The hot station was good since they cut your beef and made your ramen when you ordered. The little made to order sushi rice station was not bad, However, they removed all the ice cream scoops and packed other items a little after 9pm without any announcement. The used plates and bowls stacked on the table and nobody came and cleared them the whole time we were there. Some drinks were ordered but not delivered. The restaurant was not busy and the waitperson walked back and forth passed our table but nothing happened. For over 8000 yen a person, I did expect better.