does anyone know where there is a place which fixes sat nav systems. in particular navigation plus rns e thou any will do? in the london and surrounding countys? tried audi but there gonna charge me £100 b4 they even sort the problem out? and i didnt buy it from them so its not Guaranteed it all works ok its just theres no picture on the screen (well its very very dull! and its not the dimmer switch either! many thanks!!!