I've had the problem of an empty battery for weeks. It is virtually brand new but always after 3-4 days, when the car stops, empty!
Now, hopefully, I've come to the trail of the culprit: I'm going past my locked car the other night and think, what a funny click, crack and Knartsch noises. The click, clack came from the passenger footroom and is clearly assigned to a relay. But this crackling...? Did anything come out of the doors...? Mmmhhh funny!? Somehow I came to the button for the window lifter and drove down the window a bit, which is already very strange, since neither the key was stuck and there was no ignition or engine on. Well, now it's getting really weird: every click of the window goes a bit closer and every crack stops again. This goes on all the time, even if the Fenter is already completely closed.
So it looks like the comfort closure is somehow self-contained. The fact that the battery can withstand this load, i.e. to constantly supply all four motors of the window lifter, for such a long time, is already amazing.
The lighting of the window lifter switches in the armrest of the driver's side, flashing exactly in the clock of the relay. If I put the key in a door lock and hold on as if I were constantly closing, it will eventually stop. So somehow seems to be connected with the Reed relays in the door locks. Maybe there's just a shaky contact or humidity somewhere...
But I finally know why the battery is always empty. Now I just have to find the "real" mistake...
This just as a little storry on the edge so you don't get bored.
merci 
