Try to have a parent talk to the supervisors. It works sometimes. It also depends who is incharge because on different cruises I have been on, there have been supervisors more strict and others are more laid back.
Age on the Voyager when I went was 18. I believe when the ship is docked at port in US waters, the age is 21, but when they get into international waters it's 18. Not sure about the other lines. My post about that question got deleted, so I don't think that this is a good place to talk about that :-\. I'll just have to find out when I get on the ship then.