I won a free cruise too at a fair drawing.
They just wanted to charge me what they called port fees and taxes. There was a block of dates to chose from.
So untrusting skip tracing tax collector that I'm I ran a yahoo search on the company name. All kinds of interesting things popped up. Mainly once they get your money for the port fees you have trouble getting it back and they keep not having space on the ship to book your cruise. I found the perfect place to file my free cruise. BTW it was a 1A room on Carnival 4 day and the port fee was $250.