My refrigerator was 50 degrees so I called samsung, by the time someone called to set up appt. two days had passed and it was cold again. Worked for two weeks and then was 50 again. Called them back and this time it was 6 days before they contacted me and it was working again! A repairman came out and send to blow out the coils, I did that. He said if that did not work to defrost the unit. The freezer is cold but not as cold as the setting. Should I defrost?