Mark
I had the same problem and put it into my search engine and it took me here to this site. It seems its a common problem. I followed the previous instructions last night and hey presto after an hour it was up and running. The only downside was that a lot of the stuff had defrosted so had to throw it away but it saved me calling out an engineer. To recap what I did. Switch off the freezer and take out all the drawers and ice tray.At the back of the freezer is a plastic panel, carefully pull the panel off which is held by a series of plastic clips. You will be faced with a polystyrene sheet with the fan at the top and a small opening at the bottom. This opening will be probably be blocked with ice, as mine was. You can either let it defrost or as was suggested by someone else get a hairdryer on it to speed it up. Have a sponge and a bowl at hand to remove the excess ice/water. I did use a knife very carefully, to ease the ice away in between using the hairdryer. Eventually it clears and as soon as you switch it on you can feel the cold air circulate. As the air was unable to circulate previously only the top part of the freezer was still cold and as you say using the super freeze only worked temporary. I will make sure in future to defrost it and not assume it does not need one. Hope this helps.
Steve Mann, May 2008