Sorry to hear of your misadventure. Hopefully you paid for the trip with your credit card and will get most of your money back.
In my opinion, the only policy to follow is never to buy anything from someone contacting you over the phone or even on the internet. If you did not solicit the offer, just say "No." It is simple as that. Nothing is free. If they had such a great deal on cruising, they would not have contacted you because people would be beating their door down to take their deal.
Good luck and let us all know how it comes out,