Sorry this has happened to you. I am sure you were looking forward to your cruise.
This is problematic. I think the best analog here is that the fraudulent gift cards are forgeries. So if you buy something with forged cah, even if you did not know it was a forgery, it is not really cash.
All I ask is a tall ship and a star to steer her by; John Masefield
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014, 2016
Sail Windjammer: Mandalay 2017
Star Clippers: Royal Clipper 2015