GU demands a price increase on the entire house

Since we already have a long history of suffering here... Signed at the end of 2019, hoping for a quick development of the building area.
At the end of 2020, the first price adjustment of just under 4% came, and the world was still ok.
At the end of 2021, the fixed price period expired without anything happening in the construction area or on our little patch of mud, then there was a sharp 15% on top. We were told it was actually 20%, but since they liked us so much, blah blah... well, whatever.
In 2022, the price was "only" raised by just under 5%. I always see online what a house costs with basic equipment in my region...

2021 really was the worst year to start building... or in our case, not to start in time...

And now there is another reminder that neither the general contractor, nor the craftsmen, nor anyone else does all this out of charity, but to make money with it. If you don’t make any money from it or even have to add something extra, you don’t have to do it and can just stay in bed in the morning...
Some of you certainly depend on customers accepting price increases, because otherwise you might as well give up right away. Always keep that in mind.

Although not 100% on topic, but relevant, an email came in today regarding a price increase (on our part to a customer) and how to deal with it:

"Dear Sir or Madam,
we were informed by you in writing on xx.xx.2022 that as of 01.01.2023 the XXXX costs will increase by 4%.
The resulting additional costs for us cannot be compensated by a fixed budget from our cost bearers. Therefore, we cannot initially accept the price increase and would ask you to review it once again.
We are fully aware that your company, due to the current economic situation caused by the global pandemic and the war in Ukraine, and accordingly price adjustments, also has to cope and respond. However, in the interest of maintaining a good ongoing cooperation, we would like to ask for a review of the planned price increase.
We would like to reach an agreement with you and are available at any time for a personal conversation by appointment.
We thank you in advance for considering our proposal and remain
with kind regards"

Note: With this customer, no contractual price increase had been agreed (usually about 1.5% annually with other customers). Most customers usually have "Standard EVB IT contracts" with us.

One more suggestion for the conversation tomorrow: if the general contractor wants an increase, it would actually be customary for him to present his actual calculation to you and justify the increase based on that. Otherwise, it is a very one-sided conversation when he says 50k, you no 10k, he no 50 but maybe 30... etc. etc...

The price increase must be justified realistically—what actually became more expensive for the GC in YOUR house—I would find it okay to add on if I see that the GC did not incur additional costs that he cannot absorb himself—he is not supposed to be giving me anything for free....

That is what I meant in my post earlier. Just with less fancy words.

Which of your posts do you mean?

Cf. my explanation in post #49: a tranche of the payment plan is not equivalent to a phase of performance that could be partially accepted or otherwise quantitatively assessed in its value.

De facto it is. The payment plan is precisely linked to the completion of certain services such as the roof, shell construction, etc. The costs are incurred by the general contractor predominantly at the time of performance and not only at a later acceptance. Otherwise, the agreed price binding would make no sense at all and could, in my opinion, be considered unfair or a violation of good faith. This is just my layman’s opinion. To what extent a dispute here would make sense is another question.

I find it difficult to pay a price adjustment for installed trades retroactively. I would not sign anything and let him come. How much money have you still withheld?