Evening sir, you need a gearbox specialist to solve this as there is a electronic valve system or other part that sounds fautly.
I’ve used this company on my previous 535d where they replaced my torque converter due to hunting revs at around 130k miles.
http://www.staautogearbox.co.uk
On my current car they also changed my gearbox fluid and filter (metal replacement) at 70k miles, perhaps a call to them might shed some light?