Bosh KGU3420GB/01 fridge part no longer functioning

My Bosh appliance is now about 5-6 years old. It has been workign faultless until just the other day, Friday. The fridge portion will not drop below basically 11 degress C while the freezer is happily at the set temperature of -22 degrees C.

If I switch the appliance off and then on again I see no real difference in activity. I activate the S button for super freeze and the freezer temperature drops over time and will keep on going, the fridge temp drop slightly I think as a knock on effect but that’s about it.

I see threads for similar problems to other Bosh model but none to this one in particular. Thus could this need a simple by-pass of the thermister or a long period of shut down, that I see has worked for the other models.

Any help will be apprciated.

Oh one more point I guess the thermister will be in the fridge unit at the back as this is the onlt parts that can readily come to pieces as I see it???