The developer does not build according to the plan

It is a notarized purchase contract. We bought a house from the developer and configured it before the purchase. In the purchase contract, a house according to a specification of the construction company was bought and additionally there was a special agreement. But I have now clarified it with them. They have now noticed the mistake and will correct it. I can live quite well with that. We will get our original wish fulfilled.

But as a buyer (BT) you still cannot impose a construction stop.

Maybe it is easier to first build all the houses according to plan and then afterwards cut the holes bigger. (Although it doesn't make sense, it would be possible.

I am not a professional here. But if the contract is not adhered to, poor performance occurs. The customer is now entitled to repair or compensation for damages.