Sorry for your bad first experience.
That trailer was high on our short list.
As far as the paying... that's just a hollow upcharge. The dealer doesn't assemble the rig, so connecting the ducts and hoses is a flaw from the factory. They SHOULD check it, but I think in this industry, it's unlikely to be well done... if at all.
My trailer had a leaking hose under the sink that I found the first night camping in the driveway. You gotta expect a little something here or there, but within reason. I would certainly complain to them and have them fix it all, but you won't get your money back. :(
Personally, I think there is an up side... these sorts of things make me crawl through my camper and understand every system, front to back. So when there is an issue and I'm 500 miles from anywhere, I know how to fix it and have the right tools along to do it.
Don't let it get you down and happy camping.
2013 Winnebago 2301BH-Red
2012 Ram 2500 Megacab HO CTD