When braking to stop there was sudden acceleration that braking could not control resulting in hitting the rear of a stopped car in front of me. This has happened in the past with no warning. It usually happens when braking, but not always. I have had the car to a Ford dealership twice with this problem. They claim they can find nothing wrong with the car. I took it into them today after this incident. They would not even look at the car. Said that Ford had no bulletins on this and said that I was on mu own. I see online that there has been a class action lawsuit against Ford about this. This could be a life-threatening problem. What do I do?