Automatic gearbox ECF defective, room Hamburg

Moin moin,

my dear good AUDI A6 4.2 no longer drives, as the Tiptronic gearbox with ECF letters from ZF is defective.
When driving stage D is inserted, warm transmission oil does nothing at all, only from 4,000 rpm on the car moves so slowly (as on a rubber band).
R is a bit better, but it is also a more obvious slip.

The transmission has 240 tkm on the clock, all 100 tkm the oil and the filters have been changed.
The mistake occurred suddenly.
A lot of driving around this weekend, it turned off buttery, all right.
Monday morning to work, the Tiptronic has already switched off (from the 1st straight into the 3rd) and jumped into the emergency run after a short time (all gear displays glow).
Manual switching was also no fun, the gears banged and partly only idle.
I stayed on the way home after 10 km on a crossroad and could only move with a lot of gas from the crossroad.
Now the car is towed in the garage and the season is over (seasonal license plate only until September).

I'd like to make the car float again, Legan without AUDI is kind of not that horny.

Does anyone in Hamburg know a workshop that repairs such transmissions or installs replacement transmissions?

I have been offered a ZF replacement gearbox by the BOSCH service (directly from ZF), but should cost 5,000.00 EUR with installation.
For this I drive the car too little (only about 2,000 km a year) to put in 5 bills. Selling and rather giving away comes but not so well, after all I had the last 170 tkm much joy with the car.

If you know someone who specializes in gears, you can give a tip.

Best regards

Martin