I first wrote Carnival about this after talking to my TA. I received a reply asking me to call the number provided. I called Carnival as instructed in their reply email. And, tried to use the advise given on this post. No luck. I was told that the law about gift certificates not expiring in California didn't apply because Carnival is based out of Florida.
I still have not received my certificates back from them with the letter of explanation as told that I would. Yesterday I called again and was referred to yet another department. I held my ground and insisted that I receive a call from someone today! The rep said he was sending the request for a call back by email. I requested that he copy me at my work email. I have not been copied on the email. And, have yet received the call.
I'm sorry for venting here. I'm most likely out of luck on this. Just please be very careful with these certificates.