Q&A

Try another dealership.
Only thing that can be done at this point is to check faults and test schedules relative to the fault code provided by the BMW tester. Several things may be at fault from my experiences, in order of cheapest and simplest-

-User error (left foot braking:BIG NO NO)
-driving style/adaptations (conflicting trans adaptation) - Corrected by resetting adaptions
-vehicle integration level (conflicting software) - Corrected by updating the whole car integration level/software
-trans plug housing leaking (oil leaks through the pins at the trans plug, theory is shorting the voltage sensitive can wires) - Replace trans plug housing and clean plug connections
-oil level or quantity (oil level is to be checked "cold" and it is quite normal for the oil to be dark brown, but not grey or black) - Top up fluid with BMW lifetime oil or change it altogether, expensive
-faulty mechatronics - replacement is the only remedy
-faulty transmission - replacement is the only remedy

Going with this information, memorize them, quote them to another dealer ship when you visit with your complaint, just to show you know what you are talking about and you don't get bamboozled.

Goodluck

Try this: Insert key (DO NOT PRESS THE BRAKE YET) press start, then press and hold the gas pedal ALL the way to the floor for 25 seconds, then release the gas and start the car. When you drive your car should shift like the day it rolled off the assembly line.

we own 2004 745 same problem had the transmission oil checked and replaced it was low on transmission oil these r sealed transmissions but u can add oil from the bottom and that solved the preoblem