In Jan 06, my Ford Puma (51) failed to start. Fords have had the car and changed the relays. I have the car back but every 2/3 weeks the car has been a non start and Fords have had the car back. Today, it wouldn't start (this is now the 5th time) and the car has been towed to the garage. They have had the diagnostic computer on the car but no fault is register. Can you advise