Palazzo reservation didn't have Grazie number upon checkout: how to claim points?

I stayed at the Palazzo in Las Vegas last weekend. The room was booked through a third party so it appears that the hotel did not have my Grazie number upon check-in. A few hours after I checked out of the hotel, I called the front desk to confirm that the Grazie number was attached to my reservation and was told it was not. I asked if they can add it to my reservation so I can get points for room charges and was told that they can't touch it because I already checked out and they transferred me to the Grazie Club. The person at the Grazie Club said they can't do anything about it unless I stay at Venetian/Palazzo again and then they can credit the missing points to my new reservation.

QUESTIONS:
1. Is what the person at Grazie Club said true or is there a way to claim missing credit like there is for airlines/hotels?
2. If there is, how can I claim missing points for my room charges?

That doesn't sound right. I'd say call Grazie Club again and ask to speak with a supervisor.