I have the same fault with the  same model and, at this minute, have the cover off the back of the freezer compartment.  
Where is the thermostat so I can check it? My model has a software settable temp for upper compartment.
People have suggested it's to do with the two thermistors on the evaporator but I don't want to spend if it's not necessary.
                
 lyner
                
 July 2006