I hope you used a credit card. If so, take the suggestion from John_1 and make your life easy. If they won't be reasonable write your credit card company, copy the dealer, and they will reverse the charge. Then wait for the dealer to call you begging to rectify the problem.
Demo dispair
I hae just bought a pair of Audio Phyic demo's from a dealer in Wisconsn, I was told they were in perfect shape and could fill out warranty card. Well no material in box, includig warranty card. Several dings(cracked wood on top of speakers) and a fried tweeter. I can see that the tweeter was damaged and some kind of repair was attempted. So the dealer was well aware of the problems. I haven't contacted the dealer yet due to the time of discovery, they are closed. This truly sucks.