We unfortunately have had the experience of being bumped from a Family Cabana, which I had booked over a year out from the cruise. About 30 prior to sailing, I received a call from our PCC apologizing for having to bump us to a regular cabana because someone (very important) with a lot of time with HAL (read lots of money over the years) demanded it. My reaction was disappointment as we were traveling with friends and the larger cabana would have been convenient. In the grand scheme of things however it had little impact on our cruise. All four of us were permitted to use the cabana and we had access to all the perks afforded, especially the amazing stewards. I'm not sure there was any substantial compensation, possibly some OBC. The experience left me with the knowledge that notwithstanding our 26 cruises with HAL, our value to them is less than those of others. I refuse to stress over that and merely take it into account as part of my cruising experience.
We love the cabanas and will continue to take advantage of them.
As to the original post, you truly have my sympathy because you should not have been treated in that manner. I hope you receive acceptable answers and compensation, and are able to enjoy your cruise. We really have so little time to enjoy ourselves these days. Best of luck.