Like already said, walking out on the deal at least for that night would have gotten their attention. That PDI guy gets paid by the hour so he should have been willing to answer all your questions.
I'm sure the GM or even the owner would love to hear from you and know they have a huge problem with an employee. I would send an email first to your salesman / GM and see where that goes first.
Tell them you will be back at your convenience to have another PDI done but with another unit like yours so you don't have to drag your back up there. I'm sure you will figure it all out but your questions should have been answered.