hello , ive a 2006 , 2.7tdi , the air con control unit is 4F2 820 043 N, one of the rotary switches is playing up , it seems this unit can end in various letters , ie P ,Q,M, im trying to find a unit that has the same switches,( i bought and returned a "Q" unit as it had different switches)as im only going to replace the switch thanks piperdog