Steering Is Tight problems of the 2014 BMW X3

I recently purchased my first BMW in October 2013 at a dealer in florida. In March 2014, my husband and I were traveling when suddenly the steering wheel stopped working. I was completely unable to steer the car, so we stopped on the road. We immediately called BMW service center and were reassured that this was a known problem. We were told to restart the car and continue to drive. The steering wheel worked again temporarily until 2 minutes later when it locked again! this time we were on the highway and you can imagine how terrified I was. I could not even change lanes the steering wheel was so tight. The second time I called the service center and still was reassured. I was advised to bring the car in during the next week. A third time I restarted the car and tried to take the next exit ramp off the highway, when it happened again. I narrowly avoided an accident because the car almost drove off the ramp since I couldn't turn. I called the service center and told them we were coming now. Looking back on the situation, I wasn't offered a towing service to get my car safely to the BMW service center and it just seemed as though the problem was not being taken as seriously as it should have been. My husband and I switched because I was so scared because I did not have the strength to turn the steering wheel even an inch on a busy main road. The main reason for this letter is that to this day that I still fear that this can happen again and it can happen to anybody. I spent well over $50,000 on my first brand new BMW, and I no longer have the confidence to feel safe in my own car. BMW played down severity of my experience. I narrowly avoided accidents on the highway when the steering wheel effectively locked on me. I am not looking for an apology, but rather I am looking for some sense of security and an investigation by BMW since this may happen to more people.