Samsung RS21 freezer not freezing luke warm?

I have a Samsung RS21 American style fridge freezer - I have had the problems with the fridge not cooling and have found out how to fix that so that is fine now but the freezer section is also playing up the freezer is luke warm and not freezing at all. Does anyone know what might be causing this - as I can not afford the £100 plus call out fee for an engineer

Dawn
July 2013