I’m so happy I found this thread. I became diamond in 2016 and used all of the diamond perks for a 15 day 2017 Hawaii cruise EXCEPT the category upgrade.
i just called Carnival to see if I could use it for my booked May, 2020 Radiance Med cruise. The first agent I spoke with said “No”. She said that the promotion linked to my VIFP number must have expired. When I explained that I wasn’t calling about a promotion, but calling about a Diamond perk, she put me through to the Diamond desk where the agent upgraded me from a 6A ocean view to an 8D balcony. This is a significant upgrade. It would have cost us more than $900 if we booked this cabin without the perk. Moreover, the agent told me that if we cancelled this cruise, the perk would be ours to use on another future cruise.
Thank you Carnival!