New construction of a solid house on an existing cellar

Hello dear forum,
I have a plot of land in the southwest of Berlin including a fully basemented prefabricated house from the company Streif Haus, built in 1970. My wish is to remove the house, keep the basement, and build two full floors on top of it. All construction descriptions, plans, and floor plans are still available.

After the first inquiries to construction companies, I was immediately told that they generally do not do such things and only "desperate companies, who probably urgently need contracts" would take on such a project. He himself (owner of one of the companies) also said he doesn't know anyone in the Berlin area who builds on existing basements because it is an "incalculable risk regarding warranty/guarantee" and I should give up this idea. - However, he would gladly build a new basement for me.
I do not want to rule out that the gentleman is right, but I also think that he is not spreading this information without self-interest.

[*]Is there anyone in the forum who has realized a similar project?
[*]Does anyone know a "desperate" company, or at least an engaged one, that would take on such a house construction?
[*]How would you try to approach such a project?

I had actually already planned to consult a structural engineer and of course have a new static calculation created, since the units (e.g. Newton instead of KG) and also the limit values for loads have naturally changed, but if they are all so fed up that such an inquiry is categorically rejected, that doesn’t seem to improve anything either...

Even if it may not help very much, I have nevertheless attached the floor plan of the basement, as well as the construction description of the basement and a few pictures.
PS: The basement blocks are HBL 50

Thanks for the help
Berlinho

Given the currently very good order situation (construction boom), I would assume that desperate companies with capacities are either on the brink of bankruptcy and are now trying to stay afloat by accepting as many projects as possible, or they are simply botchers.

which incurable diseases does the Streif house have, such a house should last at least 100 years

Building on existing basements is not that unusual after all. It happens quite often in our area. I can think of 1 timber frame, 1 solid wood, and 2 solid construction companies off the top of my head. Neither botchers nor on the brink of ruin. Helps you very little.

Whether a basement is new or an existing basement with structural documentation makes no difference from my point of view.

I have a plot of land in the southwest of Berlin including a fully basement prefab house from the company Streif Haus, built in 1970. My wish is to remove the house, keep the basement, and build two full floors on top of it.

Then do that, but let’s first discuss why, in your opinion, the existing house is not suitable.

After the first inquiries to construction companies, I was immediately told that they generally wouldn’t do something like that and [...] The owner himself (of one of the companies) said that he wouldn’t know anyone in the Berlin area who builds on existing basements because that would be an "incalculable risk in terms of warranty/guarantee."

The market for construction companies is difficult enough to oversee, so one should be grateful for such self-disqualifiers. OKKD is nothing other than an existing floor slab. What does this "construction company owner" do professionally – build butcher houses?

Is there anyone here in the forum who has realized a similar project?

Without claiming completeness – I could list a whole handful just freshly nine weeks ago:
https://www.hausbau-forum.de/threads/angebot-ueber-ytong-bausatzhaus-bau-auf-bestehenden-keller.39957/page-2#post-514506