Samsung RS20CCVV

Hi, I’ve read many posts regarding these fridge freezers, but I’m confused about mine. Yesterday I noticed the fridge temperature ddisplay flashing 3, and I couldn’t stop it….I also noticed shortly afterwards that the fridge wasn’t cold. This morning I unplugged it left it for a few minutes and plugged it back in again. The display then showed 12, which I’m guessing is the actual temperature inside the fridge. So, after reading about the various problems people have had with this machine, I decided my fan must be frozen up. I’ve just had a look and it’s not. There is some ice on the cooling elements, but the fan spins freely and definitely starts when you close the door on the freezer. In the fridge side I took the panel off at the back, and the little flap mechanism works but I’m still not getting a cold fridge, and the freezer is getting warmer by the minute. Am I missing something? The fridge itself is 2 1/2 years old. Someone suggested holding down the two buttons under the display panel at the same time to see what happened, but all that happens is after a few seconds the display flashes, then the display goes blank and stays that way for about 30 seconds.
Any advice much appreciated.