Frig & freezer not keeping temp

Our GE Profile is not cooling properly. The temperature in both the refrigerator and freezer seems to go up and down. Ice and food will melt and then refreeze. We turned off the ice maker so that no longer melts and leaks out. The top sections seem to be the warmest. Right now the temp gauge on the outside says the freezer is 0 but the bread on the top shelf is not frozen at all. Any recommendations on how we can fix ourselves?