I have a 12v socket in the boot with a 100w inverter. I have replaced it a few times as the socket has had to be replaced a few times and the dealer has said they won't do it under warrenty again.
I have tried to find the fuse for it just incase it is just that, but it isn't mentioned in the book or anywhere online. It mentions the 2 in the front of the car, but I'm not sure if it is run off one of them.