Kia Sonet HTK Plus

In 2 years of driving over 25000 km, I have had several bad experiences when the vehicle has stalled suddenly for no reason. It would not start for around 20 minutes and it has happened 6 Times. I have been stuck in traffic and have had a terrible time. Have reported the matter and even taken the car to the service station, but they have said that it is in good condition and have still not been able to find the reason for this regular stalling of the vehicle. I need to have the car replaced and this complaint is to proclaim that if there is an accident because of this defect the company will have to bear the cost and be responsible.