It's kinda funny because it is simpley hard to believe that people would do this. in BMW dealership. in USA. WHAT THE FACK? No really who they think they are??? Honestly get on the phone to BMWNA and complain. That's what I would do. I mean it's one thing speaking up and following up on your rant, another is trying to intimidate you although by sound of it it didnt really work, more like surprised you that it's actually possible to do this.
Really, if you were mad about the previous thing, do something about this one now. At least call up and register your complaint. Who knows, may be you are like 101st person to do it and it will be last strike for these guys. What they did is just not on.
Stock '07 Z4 3.0si - Titanium Silver/Black/18s OEM 135M