new Audi A8 driver with problems....

Hello, everybody.

I bought an Audi A8 3.7 liter Bj.95 3 weeks ago, after exactly 60 km I had a gearbox damage on the highway. I had the car dragged right into the workshop where it was re-extended by the previous owner last year.
On Tuesday, after 2 1/2 weeks, I was finally able to pick up the car again, only with a new problem. The guy at the workshop said my servo line was rusted and would spray the servo oil out.
Sure I asked if I could go home with it from Würzburg to Stuttgart and he said yes but I would have to empty oil then.
Said done, I fetched the car and noticed that after exactly 5 KM the complete servo oil was gone again. But I drove home to Stuttgart WITHOUT servo and ordered the servo line from the Audi next day for a proud 197 euros plus VAT. Then I drove the car on ramps to see if I ordered the right line, emptied servo oil and looked at the lines but nothing came out. Then I noticed that the oil runs out on the right side and not dripping but running. So there looked and saw that the inner Manchette had a slight crack and noticed that the lank transmission is defective.Now I ordered a new overhauled steering gear for almost 300 Euro plus 100 Euro old part pawn on the Internet.
Now comes my question!!!
Who has ever developed a steering gear with the A8 and can tell me what I have to take into account( can I remove the motor and the carrier without it), already have it with the A6 Bj. 95 changed but that's not the same.
Or maybe one of you has a WHY BLEEN for me for the A8 Bj.95 , then I would have been very helpful...
Get the steering gear next week and want to install it as soon as possible...
I would be grateful for any help, because the car is my dream car and wants to drive it anyway!
Thank you in advance

Denis