samsung model rs21dabb?

Hi my panel on the front door of the freezer unit is showing the temp in the freezer as 12 degrees and the fridge temp as 10 degrees and when i press the power freeze and power cool buttons it does not cool down but I can hear the motor running if I press the temp button for the freezer it will display -20degrees for a short while and then go back to 12 degrees I have removed ice in the fridge compartment and defrosted the unit completely but this does not fix the problem I would be grateful if you could give me some advice on this problem.