I'm sure they'll get it straightened out quickly.
FWIW, the other end of the winterization stuff is under the dinette seat (should be a sticker on the front seat). Two screws and lift that plywood, pump is under there, and winterization hose is there. Between those valves, and the valves at the water heater in the back, should be just about everything you need to deal with routinely.
We're having a problem with ours -- the tank has to be very full or the pump sucks air. It's weird. Totally full and it's fine. But as it runs down, it starts sucking air while it's still full enough to read 4 LEDs on the status panel. That's my project tomorrow -- to see if I can see an obvious reason the pump is sucking air. The pickup is next to the gravity fill tube, both easily accessible through a hole in the floor underneath the pump.
But I gotta say, between this, the hard-to-close door, GFCI tripping microwave circuit, and slide that shakes & bangs as it goes in and out ...... I'm not *really* that impressed with GD build quality. Our Jayco was flawless for 5 years. I really like this trailer in all ways much better than the Jayco, aside from how crappy it was thrown together. As much as possible I try to fix it myself because I can't afford to leave it at the dealer for months.