I hope the tech draining the rear diff knew what they were doing. The rear diff requires two diff fluids in two diff areas very close to each other. The same car also had it's TC replaced but it was from another issue, down pipe touching it. Hope you get this resolved, these cars are too new to be going through that!

 

The dealer assures me the tech working on the car is a very experienced mitsu tech with lots of evolution experience and he is also a multiple evo owner. I agree about the cars being too new for this, most BMW's have the clutch as the fail/weakest point in the drivetrain. In my 11 years with them you never see multiple failures like this on a new car. I know they're not the same, but there is a lot of evo owners with these failures all over.