I've just called the Hotel. Asked to talk to the reservations department and was told by the person who picked up "when is your booking for".
I mentioned the 25th and they said "Sorry we are full". I then mentioned Plat and was then transferred to reservations.

The guy in reservations was quick and helpful. "Sure we have rooms". "What room would you like". "How many rooms would you like".

Ended up getting a "Member stay B&B" rate which is very well priced and not some "Platinum (rack) Rate".