2000 TOYOTA SIENNA User Comment / Complaint

The latest incident occurred at a stop light, on a 50 mph road, car transmission slipped twice, and then would not move. this is the third transmission. i bought it new from walnut creek toyota, a 2000 sienna. at 6000 miles, at 70 mph on the freeway, the transmission grabbed the car throwing the four of us into another lane.it was replaced. at 53,000 or 47000 on the new transmission it began to grind and it was again replaced. 12,000 later at 65,000. the last incident occured. toyota of walnut creek has stated that they will replace the transmission again. my concern is that there is a defect in the vehicle causing it to shread the transmissions. i no longer feel safe driving this car because the new transmission will fail again and this time there may be an accident. i feel the car has lost all its value.