866-227-1888 helped me switch dining times when the app wouldn’t let me. I originally booked “Anytime Dining,” but after traveling with my parents, we realized fixed dining would suit us better. When I called, the rep checked availability for all three dining slots and added a note requesting a specific table size. Once onboard, everything matched exactly what we requested. In my experience, Carnival is flexible, but the earlier you call, the better your chances.