Air Brake Wheel Speed Sensor problems of the 2001 Oldsmobile Alero

I purchased the car on 10/09/04 with a 3mon/3,000 warranty. I have brought it into the dealership numerous times for this same complaint with no luck. They have replaced the brake pads and calipers and within a 1 week of bringing it in to the dealership my abs, trac off & service vehicle soon lights all came on. I called the dealership and made an appt and while I was driving my car at 70mph it began to vibrate out of control. I had three passangers in my car along with myself. I was able to get the car back in control but if I wasn't able to I would have hit the other cars on the highway. I was only able to drive the car at speeds of under 45mph on the highway. I brought the car to the dealership the next day was told that this would cost me almost $400 to be replaced (hub wheel assembly for my speed sensor). I was told that my 3/3 warranty would not cover this part. I have researched and found that numerous people have had complaints regarding this! obviously this should be a recalled part!! I spoke to the manager at bournival and he said that my warranty would not cover this part. He said that it didn't matter if it happened two days after I purchased the car!.