skoda fabia vrs failing to start when warm

hiya guys i have this skoda fabia vrs 1.9tdi it starts straight away when the cold but soon as i drive and warm the car up to normal warm temperature i turn the car off to go into the shop amd come back to it a minite later as the car is now warm  alredy i start it amd it just cuts off after 2 seconds of being on i have to turn the key and hold it for about 10 seconds then the car turns on and stays on i have change the starter motor cam/ crank shaft sensors and also the water temperatur sensor switch has any one got any odeas of what it could be