Damn, some of you give in too easily. Why don't you just send me $170 because I say so?
There was a math error made that the OP confirmed.
Normally the dealership and finance companies have language in their contract that allow for the collection of funds if a mistake is made.
You signed the doc's with the price that they came up with and you were ok with paying.
If you have had nothing but a shitty experience with this dealership why hurry in sending them the payment? Let them spin their wheels for a couple of weeks with you. You have no intent of ever going back there do you? Remember --- Suffering builds character and it looks like they lack character doesn't it. When you finally send your payment make sure they realize that they would have been paid sooner if they weren't such douchebags in the first place.
As much as I'd love to "stick it to'em", I highly doubt 170 is going to cause any kind of stress to them. Seriously.