The other shop suggesting a whole new gearbox without proper diagnosis is unfortunately common for BMW transmission complaints because it’s the recommendation that requires the least diagnostic effort and generates the most revenue. A solenoid fault and a completely failed gearbox can produce similar symptoms at the driver level but are completely different findings on a proper diagnostic with BMW specific software reading transmission control unit data. The difference between those two diagnoses is thousands of dirhams and a workshop that goes straight to rebuild recommendation without showing you the diagnostic data hasn’t actually done the work to justify that recommendation.