Hi John,
Welcome to the forum.
I have not had to replace heater controls, but I have had the outer panel out to add an extra central locking switch (no aircon).
Some details attached (ignore engine size). More in eLearn if you can find it. (Member Ocwobio described using eLearn as "Like peeling the layers off an onion.". Look under procedures - auxilliary units.
eLearn for x244 is available in "Downloads", see black banner at top of page. Also a slightly cropped version online
here.
Also it may be possible to get access from the side if glove box removed, but if passenger airbag fitted, then problematic.
Can you indulge my curiosity, Canada is a vast country, in which provence are you located?