I have had the battery drain issue, like many others. Mine is one of the first builds too, I got it the first week the VE was released.
There have been many software fixes which my dealer has done. One of the things I have noticed was that the CD player went into a loop changing CD after CD. This was a known issue for the 6 stacker. Bear in mind that the CD player was doing this when the car was off and locked!
They ran the upgrade for the CD looping issue, and they upgraded the BCM (body control module). But even when these changes were made, I still ran flat. The reason? Once those sealed calcium batteries go flat, they never recover. I got NRMA to put one of their replacement batteries in - and I've been sweet ever since.
So the solutions?
1. Get all of the software fixes from the dealer for this issue. By now, they should know them all.
2. Get the BCM changed (if it hasn't already been changed).
3. Get a new battery.
A number of people have been talking about specific battery chargers for these sealed calcium batteries. The ones which seem to work the best aren't cheap.
Also, I have had the key replaced too. That's a common one, and the dealer will do that without asking if you are under warranty.
Another thing. When you lock your car, never assume everything is off. Keep a watch on it as I have seen silly things like the interior light never shutting off, the lights on the stereo head unit staying on etc. Take a peek once you lock your car - even with my dark glass I can still see the vitals. Some times, the only way to reset these things not turning off is to put the key in the ignition, turn it to full accessories (not start, but on), turn it off and try again.
One last thing - you can boot your car up in Diagnostic mode. To do this, you hold down the enter button ( I think, or its one of the steering wheel buttons). You hold it down, then put the car in full accessory mode with the key (ie one level before starting the car). The middle screen pops up with all cool stuff, and you can check voltage levels at different points in the car.
Hope this helps.