I own audi 1.8T quattro 1999 model. When i switch wipers on they work for a while and stop anywhere. i.e they dont stop at the normal position they might stop a third of the way up the windscreen. After about 30 seconds they start again and stop wherever they choose. The issue occurs first time the car is used in the morning but after an hours driving they begin to function perfectly. Ive changed the wiper relay wich hasnt made much difference. Has anyone had the same problem and what could be causing this?