It seemed to always take a lot of bitching to get them to do any warranty work for me, especially my windows, but with enough of a scene in the lobby they normally would change their minds.
I think you should go back to the dealership you went to and pee (or worse) on his windshield then go to St. Charles Isuzu. If I lived next to St. Charles Isuzu I wouldn't go anywhere else, I buy almost all my parts through Merlin and he's great!
I have also had the weld break (both sides multiple times) you may want to make sure your engine mounts are good. The cheap fix is to just weld it back together, but I don't think any shops wanted to do that for me, I had a freind do it.
2001 Ironman Daily Driver... 3.5" suspension lift (OME912 springs and 1" spring spacer), ball joint flip, 1.5" front diff. drop, 33"x12.5 TrXus MT, 16x10 Eagle Alloy rims, Interceptor, PV muffler, K&N air filter, Alpine Supercharger, Bilstein shocks, and some trimming.
2000 Ironman Project LS-1 VX... very slow progress but someday....... ohhhhh someday......