Planning misunderstanding / Building law

Hello everyone,
Who is liable in case of a planning misunderstanding?
We are currently having an extension built and have planned a breakthrough together with the construction company. It is visible on the drawing, confirmed by email (photos/sample pictures included).
Now the construction company says: This costs us too much!
What is the legal situation here?

Thanks in advance

Hello,
there must be a contract that contains statements regarding the service and the associated costs, right?
I can only partially follow the content at the moment.
Best regards FH

Far too little information on who commissioned what from whom and now wants to stop doing what and why?

Who is liable in the case of a planning misunderstanding?

The minister for misunderstandings in the planning office.

Seriously, what is this supposed to be about?

What is the legal situation here?

Partly cloudy.

Visible in the drawing, confirmed by email (photos/sample images included).

Well, I don't see anything like that here.

There is no general liability rule for misunderstandings.