Be warned that this property will do as little for you as they can get away with, even for a HH Diamond.
I routinely have to argue for an upgrade here, for example even when InVentry is wide open. They have a habit of checking you into your room before arrival - usually the exact room type you’ve booked - “for your convenience” and nothing but a call or tweet to Guest Assistance will change their mind to move you.
The drinks voucher will allow their very cheapest wine (house white or red) or their cheapest beer from a choice of.. one.
I personally get the impression they think they’re better than they are.