It could be the computer module that lives in the passenger footwell. I've had mine in the dealers today as the drivers side front indicator came on permenantly at the weekend. I had to unplug the headlight assembly to stop it flattening the battery.
They confirmed it was this computer module and changed it under warranty, good job really as it would have cost a few hundred quid apparently !
thanks for that tommo been told it's the body control module which sounds like the
samething you've said i am told it is in the passenger footwell too my main dealer want £246.00+vat +fitting and then they say the keys will have to recoded which is £80 not very happy as it sounds like quite a common fault