Is there a thermostat in a John Lewis Fridge Freezer?

I have a John Lewis Fridge Freezer (JLFFW1803), appears to actually be made by Zanussi-Electrolux. The fridge does not stay cool despite thermostat setting, though the freezer seems OK. I can get it to work for a while by switching on & off, but it soon reverts to a pretty warm temp which spoils food. Lights and motor do work, but it seems like a thermostat problem.

I had a similar problem with a Bosch firdge freezer and had to call out a repair man who explained that some models of fridge freezer do not have thermostats but had some other sort of computerized device to regulate temperature which were not meant to be replaced (i.e. need to buy a new fridge).

Does anyone know if the John Lewis / Zanussi-Electrolux model I have has a thermostat or one of these computer things? I don't want to waste time and money buying a universal thermostat if I can't use it.

PS - where would I likely find the thermostat? Close to the thermostat control knob? Or in the back close to the compressor?