hot to fix 2008 750li tramission fault/ mechatronic unit

What is your question?

I have a intermittent transmission fault and dealer is recommending a( new) refurbish trans with new mechatronic unit. sometimes when I drive the transmission fault kicks in and says drive moderately I was able to reset it twice but bit came back so dealer test drove it and it was a stored code so they cleared it however once test driving it again with mechanic inside he heard and felt the hard shifting but fault didn't come back on as of yet. what my best option the new trans is $7000 and just changing mechatronic unit is $3000. looking for some feedback. thanks

What makes this problem better or worse?

driving moderately

How long has your 2008 BMW 750Li had this problem?

1 month