Ford Fiesta 2014: Automatic transmission problems

I automatic transmission in my wife's 2014 Ford Fiesta started to shudder after about 12,000 km. The dealer was informed about the problem, but they said it was the way my wife drove the car and yes it's automatic. Again my wife brought up the issue at the 30,000 km service and was informed that the vehicle was within specifications. I was in the vehicle a couple days later driving along and I thought I drove over a cattle grate, the shuttering was that bad. Again it went back to the dealer to have the transmission looked at and again we were told that it was within specifications. A few days later I called the service manager at my dealer and told him that I was not happy with the service or car. He told me to take the car down and he would show me how to drive it. Yes, it's automatic. My wife took it down and was shown Ford's secret driving style. They also agreed this time that the clutch was bad and they would replace it. The clutch was replaced in June; after which the idle speed seemed higher, the gear changes seemed harsher, and the fuel economy was slightly worse. A few days later my wife heard a clunk and a there was a harsh gear change. The vehicle still drove OK. That evening she told me that she no longer wanted to drive the vehicle as she thought it would let her down because of past events. Later I also experienced what she had been telling me. As I turned to go left I placed my foot on the accelerator and the vehicle didn't go anywhere. I can only say that the transmission neutralized. I placed my foot on the accelerator harder and it took off. My concern is that if the clutch starts shuddering at 12,000 km the car will be an ongoing problem. Ford is aware of the problem and seems to be slow and reluctant to help customers who brought these cars. Do you think I have a case for a refund?