No frost or ice at the back of freezer. When I switched the appliance off for a couple of hours and turned it back on the fridge and freezer seemed to reset at -18 degrees centigrade f)or freezer and 5 degrees for fridge. Have just checked and control panel is showing two flashing hyphens for freezer and the alarm triangle is also showing. I cannot hear the compressor and the post between fridge and freezer is normal temp. For info the freezer is located in the garage adjoining our house as we have separate fridge freezer in our kitchen
Thanks for your help - it looks like I will need a fridge engineer. I just needed to be sure before any additional expenditure.