I would recommend writing:
They are good about addressing issues and getting the people involved that need to be.
Here is the regular mailing address for Carnival. You can address it to:
Carnival Cruise Lines
3655 NW 87th Avenue
Miami, FL 33178-2428
I'm glad you had a good first cruise and enjoyed the Conquest but sorry to hear that one rude person put a damper on things.
I hope you book another cruise real soon!