The Finis numbers are what you need at a Ford parts counter, check you have the right number for your car's build year.
Prices are in Euros.
To access the wire you need to remove the radio trim and the radio (don't forget to check you have the security code).
The trim pulls off from around the radio (start at the inner top corners) and take care of the plastic clips (use a screwdriver with tape on the blade or a plastic panel tool like a Bojo from ebay).
The radio is held in with 4 screws, they may be Philips type or Torx so have a Torx screwdriver to hand in case.
Pull the radio forward and disconnect the aerial (simple pull off) and quadlock (press in the catch and swing the latch up).
The heater control panel is held in with two screws that go to metal clip nuts, undo these and then the panel has to be manipulated around to get it out, if you can access the cable without removing the panel then do so as it's a tight fit and can cause damage to the large green ended vent cable.
The heater cable is held on to the panel with a plastic clip, lever this out and then turn the dial to release the tension on the cable whereby the plastic loop on the end will slip off the control cam.
The other end of the cable is buried deep in the dash where it clips onto the heater matrix, remove the passengers side kick panel from the centre console (definitely need a Torx screwdriver for that one) and trace the cable back to it's connecting point.
Edited by Stoney871, 24 March 2014 - 11:39 PM.
Corrected details and edited pictures.