I have a 91 model Passat GL, 1984 CC.
I want to fit a new rear view mirror in place on a broken one. The mirror is manually operated. It is heated. I am struck with disconnecting the electric leads connected to the existing mirror. I am not able to get to the electric point to which it is connected. I don't understand how to take out the door padding under which the electrical wires go. Any help on this will be greatly appreciated

Do you mean side view mirror? If so, you may be able to disconnect the wires behind the glass itself. You could try to get behind it by tilting it upward and looking in from below. If not you will have to remove the inside door panel and that can be tricky. It can be done but go slowly and use the proper tools. Another option is to clip the wires and cap them off. You wont have heated mirrors anymore but at least you'll have mirrors. Good luck.