If the key is repeatedly draining its battery, it would suggest that there is a fault with the key so it is continually trying to send messages to the car when it should only do this when you press the button or start the vehicle. Hopefully the dealership will be able to find the problem, as the alternative is to replace the key, which can be expensive. However if the car is still under warranty then the dealership should fix this issue without cost to you, so we would suggest pressing them to ensure it is properly fixed.