Power Steering Light On problems of the 2015 Lincoln MKZ

On June 20th 2018 while turning onto a city street at about 15 miles per hour the power steering suddenly failed locking the steering wheel. It took tremendous effort to turn the steering wheel to control the car. Because of the slow speed I was able to stop the car just before going off the road. At the same time several lights on the dash board lit up or were flashing. Once I stopped the car I turned the engine off. I waited a few minutes and restarted the car. When I started the car the steering worked fine and no lights were illuminated. I proceeded very cautiously at a slow speed the short distance to my home. As I approached my home the steering failed again, this time re-starting the car did not correct the problem so I parked the car and contacted the Lincoln dealer. The car was towed to the dealer the following day. About a week later I was notified the car had been repaired. They informed me that they had replaced the electronic steering gear. When I went to pick the car up I was informed that, on a dealer test drive just before I arrived, the steering had failed again with the new steering gear installed. I was provided a loaner vehicle and it was several days before the dealer was able to get and install a second new steering gear. The steering has performed perfectly since. This experiencing was terrifying for us as we had just returned from 4,000 mile trip, mostly at highway speeds. Had the steering failure occurred during the trip it may have resulted in a fatal crash. I am also very concerned that the new replacement steering gear installed by a Lincoln dealer under warranty also failed. Women or elderly people should be terrified at the possibility of this occurring to them. They simply would not have the strength to control the car in such a situation. The car is still under new-car warranty.