Electrolux ENN26800, fridge not working.

Hi,
we have had this fridge freezer for a few years now. It has worked perfectly. Unfortunately someone switched it off at the plug. It was then switched back on again. Afterwards the fridge section did not cool.
I defrosted it for 24hours and it then worked correctly for about a week. But I noticed during the week that the door has been left open a few times.
The fridge freezer does have a LCD control panel at the top that shows the current temperature of the the freezer and fridge. However when I placed a themometer inside the fridge I could see that the unit was reporting the wrong temperature. It thought it was 2C when it was actually room temperature. Even after it has been switched off for 24hours it still reports a temperature 2 degrees off room temperature. Could the mismatch be to with where the temperature sensor is placed inside the unit?

I'm going to left the fridge defrost for 48hours and make sure everything is dry and then try again but I don't believe it will work correctly.
I've looked at the parts list for this fridge on the Electrolux website and can't see any reference to a thermostat? Does anyone know where I can buy one?

I'm posting because the last time this happened the engineer we called could not fix our previous fridge freezer and we had to buy a new one. I've just ordered a replacement dishwasher and i'm not in any hurry to order a band new fridge freezer.