Gear type 01V - very high oil loss

I recently brought my A8, 2,8l (no Quattro) to the workshop in oil-triggering and today - after transmission expansion - received the information from it that possibly. the converter or oil pump or both are defective. and only these two parts without installation would cost around 1500,- €.
I was advised to get a used gearbox. (It seems difficult to be...)

What alternatives do you think?

It is strange that the gearbox worked despite the oil spilling out and did not make any noticeable noise. However, the car had previously been in urban traffic and on the highway at low speeds. I noticed the defect (oil loss) on the motorway using a smoke flag and therefore drove immediately to the next workshop.