Freezer works but fridge just stops working until after a defrost?

I have an INDESIT IBAN 144 Frost Free fridge freezer.



I have had this prbloem for almost a year now, suddenly the fridge stops working but the freezer works fine. In the past, I have taken off the freezer plastic compartment and taken off all the ice on it. Then the fridge works again.



But the problem happens almost every 3 months, now the fridge has totally stopped working again, but I have left it deforsted for a month now, but I am very sure that if i turn it on now, it will start working again, but stop working again after 3 months, its supposed to be a frost free appliance, and I have a feeling its just something little that is causing the problem, can someone please help me here.