Have you checked that the car has a winter pack?
I'm sorry, salesmans humour

I must admit, I was thinking coil packs as soon as I read the title. Did the dealer check the coil packs on the car in case they
were faulty?. They normally are the cause of anything misfirey on a MK4. We've changed hundreds. I'm not mechanically minded, so thats me done. Sorry
VWmd