I notice that everytime SKY add new channels to their service my Channel 4 and Channel 4+1 become scrambled. I have rang them and I have had no joy. My equipment and the positioning of the dish is fine. The problem is an intermittent one, sometimes I can receive a perfect picture for an hour or so and then for the rest of the time the picture is scrambled. Is anyone else experiencing this problem? All the other channels remain unaffected.