I'd read several posts on this, everyone reporting an awful experience. I couldn't work out the Bentley manual instructions/pictures, so proceeded to remove the blower motor, cabin air filter and flap as people had advised.
I don't think these steps are necessary.
I had already removed he dashboard, glove box, lower A pillar plastic and passenger seat in order to tape up air con flaps, replace V68 and V70 motors, pull out & clean the carpet and run cables from a newly fitted reverse camera to the head unit.
1. cut cable tie, I have taped the upper part in case I need it later
2. unscrew two plastic screws holding the foam up
3. Pull the bundle of wires towards the back seat, out of its holder
4. undo the 6mm screw securing V71 motor. When you put your head in the footwell and look up, at first you only see one screw. That is not the right one. The one to undo is slightly further towards the front of the car and half an inch higher towards the roof. It might be awkward to screw this back in.
5. Shine good headlight or torch into the gap marked X, and you will see where the white arm slots into the black arm. Pinch the white tips with your fingers (quite awkward and took me a few goes) and the two will separate. This is essentially what the Bentley manual shows.
6. Pull the motor off in the direction of the arrow in the Bentley manual diagram at top of this post and the motor falls down. Now disconnect the electrical connection by pushing the two tabs.
7. Once my replacement arrives from Lithuania, I will throw out the old one & update regarding fitting the replacement motor.
8. Finally got my hands on a working V71 motor. I shoved my hand into the space marked X above to get a mental image of where the slot for the white star-shaped knob of V71 motor plugs in. Electrical connection, check everything works with VagCom or AirCon buttons. Then, the V 71 motor just seemed to slip into the right spot. Connect lever arm. Lie down in footwell and screw in the little screw.