The common problem is the resistor pack but in this case you would still have a blower on position 4. First check the obvious fuse it will be 30A, forget the number off hand but if you search my posts I have posted it before (F63 rings a bell, it is in the box behind the glovebox not the engine fusebox IIRC, the easiest way is to check the legend on the underside of the cover. If no joy here I would next be looking toward the switch itself and if this is ok then the motor. The fuse number mentioned above is for a MK1, but as yours is a 2005 model this could be either.

As to the screens again check the fuses, back is likely to be 30A and the front has a fuse in the engine compartment fuse box which is a big fuse (Around 50A IIRC)

Martin