Take a look at this thread which discusses credit card disputes for a cruise not yet taken (in this case, one that was cancelled 7 months after a deposit was paid). Some of the info there as it relates to credit card disputes might be helpful.
Chase poor handling of disputing charges of a canceled Costa cruise

I'd also look at the Florida Attorney General's website and see if there might be anywhere there you could complain. With the amount of money in play, a consultation with an attorney might also be a good idea.