OK, I checked it out, first question, what catagory did you purchase, the 1099.00 price is for catagory 'Z' Guarantee. Is that the catagory you purchased or did you choose a stateroom. This is an inside special running which actually went into effect on the 18th of September. Here are the some of the rules of this special:
ALLOW BOOKINGS TO BE CONVERTED - YES
ALLOW GUARANTEE CABINS - YES
PASSENGERS 3/4 - NO
CHILDREN - NO
BOOKING VALID FOR-CRUISE-ONLY
AIR/SEA BOOKINGS - NO
So if you fall into the above rules on this then Yes you should be able to get this converted. As long as you are not purchasing your air through RCCL and there are no children traveling with you then RCCL should honor this rate code for you. But, since you are so close to sailing and if you purchased a higher catagory to start with, then you may not qualify for this rate since essentially you would have to cancel the original booking, which would be in penalties and then re-book at this rate. If you were outside penalties, then it would be just a matter of changing the booking over.
Good Luck, check you paper work out and see if you actually purchased the catagory Z guarantee rate if this is the actual rate you originally purchased at then you might have a chance, but if it is not, then as I stated above you would have to cancel the original booking and re-book at this rate which at this time penalties are 50% of total cost.
Good Luck, hope this helps.