Transmission replacement

[BBX5]

I have 2008 3.0dXdrive e70. One day,while cruising, the transmission skipped (do not know how to describe it) and I had to lower the speed and the car then went into Limp mode. Means the X5 stuck to the 2nd gear. I stopped again, shut the car, restarted and it behaved as if nothing happened. Same thing has happened few times. i dread to do an overtaking manoeuvre, lest it skip then I have sent the car to the authorised workshop and they have diagonised a transmission issue (5th gear clutch slippage issue!!). BMW says that the transition needs to be replaced. My car has done on 65000 kms (abt 40000 miles) and this They are not willing to replace it under goodwill too. It costs a bomb to replace it in India. Is this normal for a company like BMW who claims to take pride in its engineering!! Pathetic is not the word. Much earlier Mercedes had replaced the air condition compressor and condenser free of cost after 6 years of use and that too without asking for it under goodwill. Where Can i get the spares for the ZF GA6HP26Z 6 speed auto???