Whoops! Just saw your followup post below (You should have put it into the same thread)...So, it was the Western Caribbean, then...
I have lots of questions:
What IS the "prevailing rate"?
Remember, your original cruise was a 9-nighter...
The new June 2 is a TWELVE-NIGHTER:
>>From Amsterdam, Century presents roundtrip 12-night Baltic cruises on May 21; June 2, 14 and 26; July 8 and 20, with calls on Copenhagen, Denmark (overnight); Oslo, Norway; Stockholm, Sweden; Helsinki, Finland; St. Petersburg, Russia (overnight), and Tallinn, Estonia.<<
Now, I've been to the Western Caribbean and I've cruised the Baltic...and in my mind, this is a GREAT itinerary...St. Petersburg alone is worth doing the cruise for...Tallinn, Estonia is just marvelous and Copenhagen is one of the best cities I've ever visited...
What about airfare? Did you make air and hotel arrangements through Celebrity or on your own? Are they cancellable or changeable? What are your complete differences in cost? How early did you book?
Look, I might take it as a sign that the cruise gods really want you to visit the Baltic...trust me, it is one unique and outstanding cruise destination...But, obviously, it's a completely different trip than the one you had planned...Unfortunately, these things happen...I once got a great deal on a cruise right after they redeployed a ship slotted for the Med to Mexico instead...
I'd start "negotiating" with Celebrity/RCI...see if I could get some better alternative than just a $200 credit...maybe something based on some good faith for what WAS an "early booking" discount (assuming you booked at a great rate some time ago) or the fact that you relied on the deal you booked and spent unrecoverable money on other aspects of the trip...Don't know if it will work, but I'd give it a try...They, and their sister line, Royal Caribbean, both have other ships going to the Caribbean...or it might be a good time to check out Europe!!!
Good luck...