I have a question asking for advice. I have an NC5 attached to a Cat. 6 hotel (previously cat. 5) in At the Wailea RI in Maui in December. I also booked dates in January because I wasn't sure which one I'd be doing. Turns out January will work out better.

As I understand, these are the steps:

Call Marriott Rewards (does it matter if I call the UK office or the US one if I'm not upgrading? )
Ask them to detach but NOT cancel the certificate... DETACH.
After confirming, ask to apply the Certificate to the January reservation ( it currently says 300,000 points... but I booked it when it was cat. 5 )
After everything is said and done, and confirmed, feel free to cancel the reservation.

Should I spoon-feed the agent, or explain the whole thing first?
Is there any language I should use that will help ensure they DETACH the NC5 and not CANCEL.
Is there any language I should use if they say I can't apply the cert to a cat. 6 property (it was cat. 5 when booked)?