Auto Lights/rain Sensor Intermittent Fault

[MickG]

I'm having an intermittent fault with a 1 year old Fiesta where the auto lights and rain sensing wipers fail to manual and a message appears on the screen to tell me to get it fixed at the next service. At the service they couldn't find a fault.

It then started occurring almost continuously as soon as I drove out of the dealers so I took it back and they found a fault but apparently couldn't fix it there and then, but they cleared the fault codes and the problem now happens less frequently. It was booked back in today to be fixed and I've just been informed that they can't find a fault so can't fix it! Its a 30 mile, 1 hour round trip to the dealer so this is getting annoying. Any suggestions I can offer to them on how to do their job?