Was there any warranty offered when you purchased the coach? It’s apparent your dealer isn’t willing to accommodate you in any way without charging you. But check your warranty or other guarantees that may have been included in the purchase. You may have recourse there. It’s paramount a certified RV service tech inspect and rectify that leak as quickly as possible. Unattended, the leak will only get worse and more structural damage is likely. I wish I had better news, but barring any structural deficiencies in the room itself, it’s apparent the seals have failed and that they are in need of replacing.