Scandinova fridge/freezer problem

Can anyone offer me some advice. I’ve got a Scandinova FF6-6845 firdge freezer which we’ve had for a few years. However for the last few months the top 2 drawers in the freezer compartment don’t get cold enough to freeze any items. I’m asumin this is because the overall termperature in the freezer is too hot and only the bottom 2 drawers are cold enough. I’ve obviously turned the dial to make it as cold as possible, but no joy. Is this likley to be a simple thing to fix, or is the freezer likely to be knackered? Tks