Thanks for the reply and I will no doubt need to call an engineer.
However, I would also like to better understand how it works.
As I say, I’ve found the evaporator coils behind the back of the freezer.
But I can’t see any coils behind the fridge back, and I can’t see any way of getting air from the freezer into the fridge.
So although I understand how all the fridges on the internet cool, I can’t work out how my fridge cools because it doesn’t seem to have thesame setup!