help? renault 5

hi there everybody my friend has got a renualt 5 which the rear wiper is not working via switch but when you use the washer it works fine but when washer is on its only works intimitently but the rear dimister only works when the washer is turned on bu8t it stops half way and you have to press it again to send it back down can anybody help as its racking my brains:disappoin

thanks very much in advance chris