Beko TLDA freezing up on the back panel?

I have the same problem as Welsh lady. My TLDA is also nearly 4 years old and is very cold all the time and constantly freezes up. The back panel of the fridge has expanded into the interior of the fridge. I have a feeling the fridge is running constantly. The thermostat has been changed, but not solved the problem. Could it be the self defrost system?