is my fridge likely to be repairable?

my fridgefreezer has power- is making usual noise. fridge is warm,and and at one pint the back wall had thin layer of ice although temp in centre of fridge 15 C. freezer temp varies form -15 to 5 C with no particular pattern. no obvious smell of gas. i tried switching off compltetely for weekend to completely defrost and problem persits.