Not had this one .. but I have had some probs with my wipers .. to park the blades the motor runs in reverse (for 1 rev) must be a problem with the relay that actuates this on your GTV .. I'm lead to believe that the relays are part of the motor unit .. so I'm not sure what you can do other than change it. As for mine .. I did nothing and in true Alfa style .. the problem went away ! :-)
Talking of wipers, is it just mine that don't actually touch the screen after 80mph, or did our friends in Milan design a car to only go 150mph in the dry? (Although I doubt I'd go that fast in the wet!)
I've been using Rain-X for nearly 30 yrs! Started using it on m/c helmet visors and then on various cars. Rarely needs re-applying but try using the Rain-X washer additive which is a rather disgusting pink colour, the sort of colour juveniles who go for Max power etc. like to paint their Novas and Saxos! Best place to buy rain-X by the way is France, where its about 1/3 the price it is here.