IF, the deal was for MSRP..then the deal has not changed.
If GM raised the price of the car to the Dealer and it is reflected on the MSRP then that is what you agreed to pay!
At least you are getting something for the price increase (back-up sensors), wanted or not. GM and ALL OTHER manufacturers have price increases throughout the year and most of the time WITHOUT any modifications on the car.:( Just get in the new Camaro you ordered and start having a little fun with it!