samsung sr s2028 cvw

Hi,can anyone help,i have a samsung sr s2028 cvw it has the usual problem of not maintaing correct temp in fridge and freezer, both the freezer and fridge are freezing up.i have defrosted both sides and when switched back on it gets to correct temprature as indicated by display panel,it then seems to get warm because the freezer defrosts and the fridge get warm.If i unplug power and them power it up again i get the correct reading on the display.Can anyone help ?