Sounds like you have a weak battery or alternator. Hard to tell which at this point. The answer used to mostly be battery, but it seems the alternators are going out pretty often now. It is impossible to diagnose over the internet! They can tell if it is the alternator with an oscilloscope. Since you are going to the dealer for another top fix attempt have them check it out!
My wife drives the 6 daily and drives around 7 minutes to work, never more than 45, usually in stop and go traffic. The battery in my car was new when I bought it as a CPO car from the dealer. It failed in 2.5 years. I never had any issues with low battery until it simply failed.
Now, with this new battery, I make sure and put it on a trickle charger at least once a week overnight. This is to prevent failure.
In my case my "non-favorable driving profile" caused the battery to prematurely crap out. Maybe this is also true for you?
As far as keyfob, I have mine about 20 feet away also, never had a problem with that.
The alternator is always spinning, it is not like the a/c compressor with a clutch/brake. It is just at idle the alternator is only providing enough juice to power the car or just a bit under so the battery is being utilized. It isn't until higher rev's that it puts out increased voltage that can power the car's systems and charge the battery at the same time.
Last edited by tampamark; 10-04-2012 at 06:56 PM.