Wrong construction company - only stress during house building

I had the constant upgrade requests because they failed to plan a complete house for me before signing the contract. What is good about a 1cm insulation under the exterior windowsill when 3cm are installed in the window reveal? I do not expect the water on the underlay membrane to be a raging river. The general contractor is rushing his subcontractors on me. Nothing is peaceful here anymore.

I had the constant upgrade requests because they didn’t manage to plan a complete house for me before signing the contract.

Sorry, but you didn’t have to sign yet. You can’t really talk your way out of it.
As for the technical part, I guess no one can say much here because the topics are only briefly touched on/have been touched on.

The general contractor is putting his subcontractors on me. Nothing is peaceful here anymore.

What are they doing? Chasing you? Biting? Honestly, I have to think of the joke about the highway.
Radio: On the highway there is a wrong-way driver.
Driver: One? Several!

Sometimes you are the problem yourself. And you can tell quite well if _everyone_ thinks the others are making mistakes. The likelihood that _everyone_ is somehow not quite right is very, very low. And I have never heard of a SUB siding with the GC. Usually they are like fire and water but dependent on each other, a so-called love-hate relationship.
As already said: building a house is always stressful! And there are no powder puffs from the contractor. But that doesn’t mean many things can’t run correctly and normally. Many have an exaggerated idea of how building a house will go (colorful advertising, tidy construction sites, polished construction vehicles, and in the end you receive the golden key to the turnkey house) – maybe you are one of those?
I also don’t know whether you really understand what you are writing here yourself:

We have at least 2 defects in the window area where even my construction supervisor says it won’t be easy to insist on this from the construction company.

To me that means: you see a defect, the construction supervisor rather doesn’t. But you make out that the construction company is causing trouble and not admitting something. From how it reads here, I rather think you have to admit to yourself that it simply is not a defect.
And as already said: relying on your crystal ball and thinking you know better beforehand often doesn’t make life easier, especially if you don’t look properly.

The general contractor is stirring up his subcontractors against me. Nothing is peaceful here anymore.

Then expect that you will be banned from entering the construction site. Apparently, you are really annoying the general contractor and are interfering as a theorist in agreements between the GC and subs.

The constant upgrade requests I had because before signing the contract, they didn't manage to plan a complete house for me.

Why did you sign then? You can also have your house planned first and then look for the contractor.

I had the constant upgrade requests because they didn’t manage to plan a complete house for me before signing the contract.

Why you signed the construction contract for a house not yet ready for signature-worthy planning requires explanation! Did you want to take advantage of a Nurnochheute price before the contract had any content?

What is good about 1cm insulation under the exterior windowsill when 3cm is installed in the window reveal?

We don’t know the details of your house – explain yourself why it should be different here!

The GC is rushing his subcontractors on me. Nothing peaceful here anymore...

A sentence like a headline in Bild, Express, or Kronenzeitung – unfortunately again without any comprehensible content.

Then expect that you will be banned from entering the construction site. Apparently, you annoy the GC to the max and interfere as a theorist in agreements between GC and subs.

If I were the GC, I would also seek a conversation:

We have at least 2 defects in the window area where even my site supervisor says it won’t be easy to claim them from the construction company. The complaint has been filed and I have withheld money.

I assume that the OP does not understand the details of the working drawings in many places and asks the "site supervisor," who according to his semi-technical knowledge googles some additional information as needed and thereby finds inconsistent rulings. In the entire thread history of the OP, I have not found a clear indication of objective botchery by the GC – but plenty of points of a diffuse (and probably treated with the wrong remedy by the "site supervisor") fear that the GC might try to keep his price promise by dishonest savings measures.

My impression – which the OP has nowhere substantially dispelled – is that here a GC – probably neither a gem nor a disgrace to his profession, but an average so-and-so – faces a layman with the ascendant of a phobic and his semi-knowledgeable assistant and perhaps should simply be allowed to do his job. Because, as said: So far the OP has not produced any proof of objective bungling; only disagreements about professional execution or even just dimensioning (mostly of minor building components). No nanogram of malice is needed for a ghost driver suspicion.

Hello,

Unfortunately, I chose the wrong construction company. There’s only trouble, and I received a call from the company asking me to come for a personal meeting again. Officially, it’s about the further procedure – but that’s not true. They are trying to use the meeting to avoid responsibility.

Also, hello,

How do you know that this is not true?

When I read the comments here, it seems important to have a clarifying conversation.

Or do you think that

I have withheld money. I have not received an answer so far, although the last deadline has not yet expired.

is well received by the contractor?
I would also seek a conversation before I hire a collection agency.

I feel so bad every time I talk to the company because I am just angry about how things are going. Besides, it costs me money again because the site manager also wants to be paid.

Then slow down a bit. The contractor is already offering you a clarifying conversation.

Could it be that you are only this angry because the change orders are throwing your financial planning into chaos?

I would be interested in your opinion.

Thanks in advance.

In my opinion, there are always two sides to the coin. I only know your side. Therefore, I don’t have an opinion here that can help further.

I could offer to help as a mediator. However, the risk is too high for me that I would then have to chase my payment.