Try calling guest relations (800)929-6400 or email firstname.lastname@example.org
They should be able to lead you in the right direction. I believe it was the Carnival Triumph last year that had the cruise I mentioned earlier. Sometimes certain events are chartered out by another company and you have to book it through them. Such as an "oldies cruise" on Costa one year. But if there is anything scheduled they should be able to give you information.