E class wiper problem

[steelman]

OK Guys - possible newbie braindead question but it has got me confused.

I have an 55 plate E220 cdi - had it for 4 months and been loving it. In the last week started to get issues with the wipers - first couldnt get them to go off, stopped engine ,started again and all well . Then a few days later while sitting in drive thought I would test them before setting off just in case. Sure enough now not working at all, even when pressing screen washer. Indicators and main beam controls which are on the same stalk all working fine. Jumped in my daughters car and planned to book into dealer to get sorted . However today 3 days later on a hunch, when the rain started I started car up and tested wipers, all now functioning. I believe the E class has some form of sensor which varies wiper response to rainfall could this be the source of my prob. Concerned that I set of then weather hits and I discover no wipers.
All and any thoughts appreciated

 

[Diesel Benz]

Usually it is the stalk that causes issues like this.

 

[steelman]

Thanks Diesel - I had kind off reached that conclusion myself from reading this and other Forums so took into local main dealer.
Day one they diagnosed Wiper motor failure so ordered one in
Day two advised that the motor had not fixed issue looked like a sam/command module problem (I think thats what they said) they ordered one
Day 3 moudule arrived but would only work with new motor, they think fault on old one had blown the old motor. Total bill including Labour £960. Lucky for me I took the extended warranty and after a little bit to and fro confirmed it was covered . All in all can't complain with the service but would have been gutted if I had had to shell out nearly a grand to fix the wipers