Help sought f. Repair coolant tube oil cooler

Hello, moin together!

I'm here looking for help for my big ship, it's a 2000 S6 4B Avant hand switch, MKB AQJ (250 KW).

The problem seems to be the much-quoted and legendary cooling water tube of the oil cooler, which seems leaking.

My guess is based on the observations I made on this:

The car loses minimal cooling water, ONLY in the cooling phase overnight, not at short notice after parking the vehicle. It's always very little, so to speak droplets.

I had my water cooler renewed in the workshop, which no longer looked really good. Unfortunately, the hope that it will be over has not come true. Today I was back in the workshop, the car was warm. After more detailed examination incl. We had to find out that the new cooler is fine, and the air condensator in front of it is also tight.

We noticed that the oil pan is rusty at the bottom of the rear edge. Even the smallest cooling water residues could be detected at the bottom of the oil tank.

As I have already researched the Internet, all these signs clearly point to this plastic tube. A cooler - leak would, in my opinion, also cause greater coolant losses.

What do you think? Is that relatively clear? Or can I test it again?

I think that's the secret. Unfortunately, I'm not a car mechanic. Things like the air mass meter, the G62, or now the Triplex antenna foot I get changed myself, I am also very interested in these things - such a car is seemingly not only a daily means of transport, but also a hobby.

This thing, however, is two numbers too high for me, I wouldn't be able to do that myself.

Therefore I wanted to ask here once in the round whether you know in the area Bremen / Hamburg / Hannover someone who has done this work more often, and possibly. I'd do it again. A fair remuneration for this scoundrel would be a matter of course for me. I could also do henchman activities. I myself live in Scheessel, in the middle of HH and HB...

Thank you in advance for your feedback, and I wish you a nice weekend!