Fails to start after a journey but when car cools down then starts smacks to me of s failing Cam Sensor which the garage would not pick up on. This sensor tends to fail when hot and start working again when cooled down.
Same for the crank sensor BUT a failing crank sensor would cause cut outs and non starts (also no flicker on the rev counter when you turn her over) - you are describing just non starts after a journey then starting does point to my mind to a failing Cam Sensor which will only cause non starts .
