Robin have you checked your original confirmation on this from when you booked this cruise?
We were booked as a Cat 7 Guarantee and all our paperwork says Guarantee including the paperwork that I printed from when I did our online check-in at the 90 day mark. We were booked as a Cat 7 Guarantee and I had been checking for our room number daily for the last few weeks and late on Friday we had our room number. We are in a Cat 7, no upgrade for us but that's OK because I made sure when we booked as a guarantee we were booked in a category that we would be happy with if we were assigned a cabin in that category like we were.
Is it possible you were booked as a guarantee and your room was just assigned, like ours was, and you were assigned a Cat 12 room over this past weekend? When was the last time you had checked your reservation to see if it was listed as a Guarantee or an assigned room?