Brake Antilock Wheel Speed Sensor problems of the 2002 Oldsmobile Bravada

On 12/11/02, I was driving my 2002 Oldsmobile Bravada in rush hour traffic and was traveling in the passing lane going at a speed of 70 mph when my speedometer dropped to 30 mph and my brake pedal was to the floor of the vehicle. Unable to accelerate. The dashboard displayed : service brake system and contact onstar displayed also. I, somehow, merged to the right lane of the expressway and at this time, my brakes were still to the floor and the speedometer was continuing to decline. Steering was difficult. I was able to get off the road, but the car stopped itself without me applying brakes. I put my car in park and the car at this time was stalled. I tried to restart the vehicle but was unable due to the car being "dead". I contacted the gm roadside assistance toll-free # to notify them of my problem and they supplied me with a # to refer to in case a tow vehicle did not arrive. Approximately, 30 minutes later a tow truck arrived and my vehicle was towed to yark Oldsmobile. I spoke with the service manager- anthony and he documented my concerns and told me that my car would be serviced and they would let me know what the issue was. I also told him the other problems with this vehicle included: rear suspension defect 7/2001, loss of brakes in 8/2001, car failing to start and needing towed or jumped 3 times since 8/2001. On 12/12, the service dept contacted me and told me that there were several fault codes. . . One being a faulty speed sensor. They pulled several codes: c0236-circuit failure vss and c0237- a communication error. I told service that I also had several issues with the electrical system and jim stated they would look inot it but it is hard to find an electrical problem because it is such a big system. I was instructed that my car was able to be picked up on 12/13/02. I did so at that time, but I am not satisfied and do not feel safe in my vehicle. Yark is aware of above.