When the car was returned I EVENTUALLY found code for wiper switch in the dashboard module - I'm sorry I cant remember what it was. Live data showed just about every switch working but live data for the wiper switch missing!
After discussion with the customer,I took the plunge and replaced the (substantial) switch.
All working fine now, but a £700 bill to fix this?
Thats why I'm still running my 1994 Passat!

Colin.