samsung sr-s2028 cools to required temp then heats up.

Hi,

My samsung is making me pull my hair out. It cools to the temp that you set it too then when it reaches that temp it stops and the display stays at the cold temp. After a couple of hours it is very warm inside. If you turn the power on and off it resets and show the correct temp. a lot warmer than it should be.

I have just changed the thermo fuse and defrost sensor and this has not helped. it seems like the thermostat is not telling the fridge to keep that temp. Is this possible?