I had a very similar experience several years ago with my previous Benz. I was also in university at the time. Same basic scenario as you. I was bullied and treated like crap. These kind of guys suss you out in a second - they can sniff your insecurity and lack of experience like a hound dog. They see a young, inexperienced kid coming in to get their car and from that second on, the ball's in their court and it stays there. No way could they treat me like that now. No doubt about it, it's a power game to them. They're not just "business men conducting business" - I got the same rude attitude, lack of cooperation and lack of respect - the things a true "business" would offer to a first-time "customer". These kind of guys have the law to back them and they abuse it, IMO. Of course, there are good companies and kudos to them, but this business tends to attract the nasty kind as well.
Anyway, if it makes you feel better, I did get back at the miserable ba$tards. Can't say how or what, but they had it coming. It was childish and stupid of me, but hey, that's what they get for messing with a young, inexperienced, emotionally unstable young adult with nothing to lose.