If you search on this forum or look for battery problems on rangerovers.net, you'll see that the RF receiver causes a lot of flat battery problems.....its a black box, near the blue amp on the drivers side rear, under the parcel shelf. Either get a new one - its easy to fit - don't get it off ebay as lots of old ones are sold in "new" boxes- cost about £150 at a stealer - or unplug the aerial wire leading into the box and use the fob up close to the car.