Another senario is that they went missing whilst your cases were being moved overnight especially if you were using the American TSA locks. It is so unusual and I am sorry it happened to you but if you point a finger it is almost certain that someone will be sent home prematurely. Regards.... neil.
If you say what ship and cruise line then maybe advice on contacting the ship could be given.
Was this a fly back to the uk cruise .
As per the last comment, did you fly home as this is a common occurrence at airports but I've never heard of this on a cruise liner. If your fairly certain this is 'Ship' problem then telephone their head office & they will contact the ship whilst at sea. Good Luck. Wilba.
If it was just gifts bought in the ports are you sure you packed them ? Seems odd if that is all that went.
I wouldnt like to point a finger at any of the staff on the ships they are all very honest because we left a wallet out by mistake with money in it i forgot to put it in my bag and no one touched it, we were going of ship and i left it behind.