Take it from me, get away from that dealer.
I read the first post, got half-way through, and said to myself, "Hey, this sounds like a clutch." I'm not very mechanically inclined and I can't believe that your BMW dealer would be that bad. If I were you, I'd recommend going somewhere else. Not all dealers are the same and getting one that has a good mechanic can make all the difference in reducing the stress level related to your car's wellfare. Its pretty damn easy to diagnose a slipping clutch and them dicking you around for a month is inexcusable.
Having a powerful AWD car, we Evo guys are used to slipping clutches and horrific drivetrain failures - my clutch lasted a mere 20k mi and that is above average. Just be conscious of how much clutch you feed and it should last longer.