As you were not given dining cards, the person in the dining room having asked you for the invitation, and you told him you had not been given any, he should certainly have not made you go back to the front desk and ask for one, he should have done it himself, and at least asked you to go and sit in the dining room whilst he got the cards. We had a similar situation in T5 arrivals, no invitation card was given to us, we just went into the dining room sat down, the person asked us for our invitation, told him we did not have one, we showed him our BP, and he went off and got the invitation, no questions asked.