Contact the Service Dept. Manager first, and complain about the treatment you've received. If that doesn't help, then contact the General Manager of the dealership and they owner.
The most common reasons most people still have bad experiences of any kind with dealers, is they are too afraid, or not sure, that going back to complain would work. They don't feel appreciated. Sometimes dealerships need feed back to improve.
If all that doesn't help, find another dealer in your area better business bureau