Engine Belts And Pulleys problems of the 2014 BMW X3

I was driving home on a city street when the engine light began to flash. I was getting close to being home so I continued to drive to try to safely get my car off the street. It then began to drive slower and slower even as I was stepping fully on the gas peddle (well below the city street limit of 35, as cars started to go around me). The car then completely shut off. I luckily had made it to a neighborhood road and was able to glide over to the side as much as possible. However, because the car was no longer operational it was still in the street and I was stranded in the rain until the tow truck got there hours later. Once I put the car in park it would not go back to neutral so I had to wait for a specific tow truck. Once my mechanic was able to take a look he said that the timing belt had broken and destroyed the engine. In his opinion this is unheard of in a car with just over 70,000 miles and 6 years old. I had just purchased the car from a high end used dealership 5 months prior and they said they found that BMW had put an extended warranty on the timing belt for 70,000/7 years for this specific issue. When I called BMW they would do nothing because the warranty was no longer in effect, even a mile over 70,000. They clearly know this is an issue with this vehicle and never properly remedied a very serious safety issue. My normal commute is all freeway. This could have been a very serious, if not fatal accident if it had occurred on the freeway.