Why not google as you can use a compute.
As Cunard is a Carnival company its offices are in the USA. Its address is Cunard Line, 24305 Town Centre Drive, Santa Clarita, California 91335-4999, USA. A letter to them might get you the address of their recruitment agency. Good luck.
If you visit the Cunard web sight I am sure that there is a sections for job applications I think most cruise companies have this on their web sight.