Wow, a lot of negative reactions about Ambassadors. While mine does not seem to know all of the rules, I am glad she responds to me in a somewhat timely manner.
As for YOUR24. 3 attempts. 1 immediate success, 1 success after 2nd 3rd and 4th request to Ambassador (hotel was not responding so she finally called the Rooms Director at the hotel), and 1 sorry we can't do Y24.
I got the benefit via merger as a Marriott member. Do not know what Y24 was like in Starwood world.