Any question specific to the car would be better posted in the relevant car section rather than here.
Heater resistor in mounted into the heater box, above the clutch pedal.
Remove the panel to the left of the clutch pedal. Now you can see the heater box, if you stand on your head. The resistor is held into the heater box with I think just one screw, and has a wiring plug onto it. High up, near the clutch pedal pivot height. Unplug the connector, undo the screw, pull the resistor out. That's the theory anyway. It might fight a bit, as some have found they change shape a bit if they've got too hot, so some swearing may be necessary.