Developer refuses to hand over documents

Who even says that the masonry is defective?

Who even says that the masonry is faulty?

I can gladly send you pictures, any layperson can see that.
Have professionals in the family, they were completely shocked.

Then just present the images to your expert.

We would like to, of course. However, the expert requires documents that the BT does not provide to us. We also want to obtain permission from the BT for an expert to enter the construction site, but we receive no response, they do not answer the phone, and the mobile phone is switched off.

The expert needs documents that the BT does not give us.

What for? - On the other hand, you write,

I can gladly send you pictures, any layperson can see that.

You only need to compare botched work with the standard, not with an execution plan.

I have to take over a house with visible defects? I can hardly imagine that. What is a handover with a protocol for?
Even a BT cannot just take whatever they want, right?
[...] it can’t be that in the end I have to buy a defective work.

They don’t answer the phone and the mobile phone is switched off.

When you buy from the developer, you’re practically buying a pig in a poke if the building is still just a fantasy at the notary appointment. By now you should urgently explain to a knowledgeable lawyer what you actually signed: a contract with a developer, a general contractor and/or a fraudster?

Well, I wouldn’t sign off including all visible defects. That’s what the acceptance is for, which then includes a protocol.

In the end, you have to buy a defective work. Defects that already exist.

Why defect? Who says it’s a defect?
I’ve already seen some walls here where the client almost died, but in fact, there was no defect.
Maybe you show a photo of the disaster?!