"In the meantime water has been streaming down the inside wall whenever it rains , who knows what damage it might be causing.
I know what damage it is causing. Your lucky in that you caught it early when you can get some help
"We are now worried about delamination a few years down the road when there is no warranty".
That's why the warranty is as long as it is. You should be worried. You have to get it fixed right. And I mean fixed to not have any more water penetration. Not "fixed" In their opinion to get them over warranty period.
Brought home new Holiday Rambler. No signs of any leaks for 3 years. One day see light reflection on wall look just a little bit different. Warranty is over at this point. Took wall apart. For some unknown reason behind the shower panel somebody decided to pop a staple into a pipe. Had to be done when it was made.
Only time wall was apart. Just barley made a drip and only when shower was used. But after 3 years a little drip destroyed a wall and part of the floor. Took pic's and talked with Holiday Rambler. Holiday Rambler was very apologetic. Apologetic to the point of giving a whopping 10% discount on the parts needed. (New plastic pipe and 1 sheet of laun and 1 roll of wall paper). And the dealer was also apologetic and would work on it "as soon as possible".
Was Holiday Rambler's bust from the beginning but took 3 years to show up.
It could happen to anybody, I've been told.
Glad you caught it early, get it fixed right to prevent problems later.