Fridge is either too warm or too cool

My Thor fridge is either too warm or too cool. I set it to say number 6 and it becomes too cold. Then i have to reduce the dial until the compressor , i think, stops.
Say I go to 4. It gets too warm then and won’t start cooling until i turn back up to 6 and hear it click on.

I have to do that every 24 hours. I used to be able to set it at a number that suited and it would come on and off and stay at that temp. Is it the cold control?