Do you have an aftermarket alarm? I've had the same problem on my old teg, I've also had my battery replaced once but it would last over a week if it's being garaged. After discussed with the technician after the dealersip, we found out it might be the aftermark alarm that has being using a great amout of power from the battery while the car's not startling. Try disable your alarm and leave the car there for a week, if the problem still exsits, disable the battery jumper wen you are not drivng it.