Liebherr CUN 3031 fridge /freezer heating

Two year old Liebherr CUN 3031 fridge /freezer heating .
Yesterday I’ve have noticed top of a freezer was slightly warm, but I didn’t raise any concern. Few hours ago I’ve opened fridge/freezer. All food was warm and fully defrosted. Instead of cooling it was heating.
I’ve turned it off, unplugged for few hours and then plugged it back. It didn’t help.
I’ve done some online research. It could be faulty thermostat
I am without fridge/freezer I am desperate to hear any suggestions.