The last time I was under my M which was last week I noticed the bottom of the fuel tank was plastic!
If you ran over something, you would of ruptured the fuel tank first not just scratch it!
I say take to another dealership.
2016 M2 on order for June 2016 Euro Delivery
2011 BMW M3 Sedan Alpine White
Picked up via ED 9/27/2011 & Redelivered 11/23/2011 **SOLD**