Just remember, if you got home and found that they made a mistake and overcharged you (monthly say), they would most definitely NOT resign the papers.
Keep that in the back of your mind, they would not do that for you, why should you do that for them?
Id say go back there and re-sign if they were apologetic and genuine, and say the Owner or the Sales Mgr called you. But for this runt to call you upset, screw him.
2016 750i xDrive M-Sport (Current)
2015 650i Coupe
2013 750i M-Sport