Daughter just bought first property and the Hotpoint HM315NI Fridge freezer is way too cold in the fridge. It froze a bottle of milk overnight. The compressor keeps running despite a fridge thermometer showing temp is close to the freezer range. Thermostat on setting 1. Changed thermostat for one purchased on Hotpoint website, made no difference. Called Hotpoint who said I had ordered wrong thermostat and sent correct one. This has made no difference either. Tried using glass of iced water to test thermostats with a multimeter but they never switch off. Could there be something else causing the problem?