How can I fix my Candy F1B fridge freezer?

Recently the fridge and freezer temps rose well above the norm, although the thermostat was untouched. However the appliance was running quieter than normal. It was switched off for a while and when turned on again the freezer appeared to work straight away, but the fridge was still the same. The freezer though eventually defrosted itself and the appliance went quieter again.

Any ideas please?