I know you're confused - that's why I asked for some details.
Can you please tell us the precise model of Receiver, and the make and type of LNB?
Can you please give us a more precise location than "UK"?
Providing these details may help in homing in on the real issue and the likely solution.
However, as the magic words Fortec Star have appeared, you may need to take due note of this Thread
Skew problem with Fortecstar LNB FSKUVN and Icecrypt 0.1db single LNB which may well have a significant bearing on your problem.
Edit: Topper has hijacked my reply ................