Problem with Zanussi frost free fridge freezer

Hi, I have a Zanussi frost free fridge freezer and the display at the top is flashing red as if there is a problem with the temperature in the freezer but it is at -21 degrees celsius. There was a build up of frost which there shouldn't be so i defrosted it yesterday hoping this might solve the problem. But it is still at -21 now and flashing red and the frost seems to be building up already! Anybody have any ideas as to what the problem might be and how i might fix it??
Thanks

Sometimes a restart can fix this, but otherwise you might need to get a service guy in for it. (Around 120 euro).

If I remember correctly the frost-free mechanism works by having a heating element on the cooling element, there’s a sensor that detects if there’s frost building up and if so melts it off and evaporates the water away. What fails is usually the sensor, and if not that the heating element.

When the frost-free system isn’t working that usually means the fridge part isn’t cooling any more. Have a check and see if your orange juice isn’t as chilled as it should be. (The frost builds up so much it blocks the cool air coming from the freezer into the fridge compartment. Your freezer will still be freezing though.)

If your fridge is as cool as it should be then my guess is probably wrong. But if your fridge is warm you could defrost manually, though it takes ages with these fridges – that’ll buy you a few days before it ices up again

Thanks for your reply redwing.
The fridge seems to be okay but i will double check later when i'm at home.
I reckon i'll have to get someone out to look at it alright unfortunately!