OP says Oyster control says "Turn on Receiver" That means its found a sat, and if the search sat is Astra2 its locked on to Astra 2. =Oyster system is working fine.
If the OP is using the TV inbuilt sat decoder it should automatically be on when the TV is on......so wouldn't show message "turn on receiver". I only get that message when I'm using my stand-alone sky box and forget to turn it on.
Perhaps the OP should check the integrity of the coaxial cable connected to the TV.