So this morning I went to unlock my 08 plate Aero 20T using one of the two supplied key fobs and nothing happened. Figuring the battery may be dead I reached for the spare, but still nothing. After much playing around I finally find that the only way to lock or unlock the car (remotely) is to put the transmitter right next to the bottom right (when facing the vehicle from front) corner of the windscreen .
Slightly irritated I called the dealer and booked the car in for attention.
Later that day I remember that we altered the transmit channel on our video sender for the TV the previous evening, and sure enough, switching the video sender off solves my remote key fob problem!!! I've now turned the sender on and off several times, and have proved beyond all doubt that this is the cause of the problem. Altering the operating frequency of the video sender also resolved it.
On calling the Saab dealer back they tell me that the key fobs operate at around 4.3 GHz, whereas my video sender works on around 5.8 , yet it's obviously close enough in frequency or proximity (or both) to cause sufficient interference to be problematic.
Interesting thing is, supposing it was my neighbor who'd had the sender? I'd have never twigged what the cause was. Worse, upon taking it to the dealer the problem would have doubtless solved itself, only to return when I'd brought it home. That's why I decided to stick this on the forum hoping that if you've searched here first before booking your car in it might help you.
My advice if both your key fobs suddenly stop working. Use the mechanical key to take the car half a mile down the road. Then try the fob again. If it mysteriously starts working again then this could be your problem, and not the receiver on your car.