Electrical problems - wipers won't turn off

My daughter has a 2005 VW GTI which has had a series of bizarre electrical problems. The latest was with the windshield wipers. Sometimes they work properly. Often, when the weather gets damp, they go on by themselves. (This is not a feature - they don’t automatically go on when it rains, it might just be humid.)



Sometimes, turning the front wipers off will turn the back wipers on. Turning the back wipers on will turn the front wipers off.



The other day, she needed to drive 40 miles to work. It was not raining at the time, but it was threatening. The only way to turn the front wipers off, was to turn the back wiper on. The only way we could get both wipers off at the same time, was to remove the fuse for the back wiper and turn the back wiper on. In the event of rain, she could then turn the back wiper off to make the front wipers go on.



We have brought the car to the dealer several times. They replaced the relay twice. They swear they have checked the entire system and can find nothing wrong.



The last time it happened, we showed them that it was impossible to turn the wipers off. They have seen the problem, but they still can’t fix it.



Any ideas?

What about the switches? Is it a combination switch that controls both front and rear wipers, or are they separate switches? It is definitely a wiring/switch issue, but may be a fault in the switches or in the wiper control units. It would be best to have someone looking at it when it is acting up.