hi my mum had the same problem,her "frost free" freezer uses the cold air from freezer to cool fridge.so a block of ice had blocked the vent so to speak .try to defrost for 24-48 hours, otherwise you may need to take off the panels, which in my mums case is located inside at the back of freezer.all working now.hope this helps.
Bramblepicker, January 2014