Your best chances are with the dealer and a lot of visits, phone calls and document EVERYTHING with words (dates, conversations, etc) and pictures.
If that does not work call the manufacturer and get them involved using the documentation and pictures to help you show what the problems are and what has been done or not done.
Then if that does not work let them know that you are going to go public and will let everyone know what you have dealt with. Post everywhere, contact the BBB and any RV associations that they may belong to.
Also be realistic in your demands. If the water pump is dead that is a actual issue. If the water pump is loud, and most are, they will not be able to help you. I know a few people that had major problems and they did get fixed after a lot of work on the owners part to get it done. Should not be required but..........