hi, my old mans got an audi a4 2002 model and for some reason the rear passenger side door is stuck shut , it wont come open , weve tried giving the door lock area a sharp tap to see if it will shunt the locking device back into position ? as explained on some of the web searches ,without any joy tho, can anybody point him in the right direction ??????? hes pulling his hair out, what bit he has left !!!!