Open door remove 2 screws in top panel,pull down the plastic cover around dial.check power is off remove wires from stat pull silver capillary wire out the hole.replace with a service stat 1.If the fridge still freezes up then the tube that the capillary runs down has come away from the cooling plate behind the fridge inside the foam.This was the cause of my problem in the end.seems a common problem on these fridges.In which case you could try cutting the foam out the back to re fix the tube,but chances of success are small as if you go to deep you will cut into cooler plate and lose the gas.
Andrew from Titcombe Refrigeration
December 2012