Your best bet is, as others have said, threaten the dealership with 1) reporting them to Ford proper for performing unnecessary and unrequested procedures on your car, 2) reporting them to the Better Business Bureau for performing unnecessary and unrequested procedures on your car, and 3) threaten to sue them for both the $56 and punitive damages. As I have been faced with the same problem here in California (I turned my car in for a tune up, and gave them Mobile 1 and a oil filter to put in.. and they added and "additive" for $30 that I did not request)
If this dealership treated you this way, perhaps they are open to a class action law suit... If you have a laywer friend, they might be interested in padding their resume by taking a case like this....
