@Piers I'm having a hard time understanding why, if you noticed it prior to driving off from delivery, you would accept it like that?
Did you take pictures during delivery that show it?
Did you ask them to document it on the paperwork as something to repair at dealer cost?
Did you have the SM or GM come over and look at it with your SA?
If not, then it is probably going to end up being a life lesson earned the hard way.
Good luck to you.