Knee wall according to the development plan

So the prefabricated house provider (seller) looked at the property with the architect. When we signed the construction contract for the Evolution 154, we said the house should look like that, just as a duplex and then twice. That would be no problem (seller), they would just have to change the floor plan a little. He also had the development plan available for viewing during the sales conversation. So he knew the exact data of the property (site plan etc.). Now enormous additional costs are coming up, then again credits, then again new cost estimates etc. etc.. Just because we are not allowed to build a knee wall of 1.60 after all (which is signed in the construction contract), we have now received a credit of €2,000. How can I check here whether this credit is justified?

Hello,

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That would not be a problem (seller) you would only have to change the floor plan a little.

This statement is sheer mockery; sorry - even as a layman, you "should" have noticed this. From the floor plan originally purchased by you, there is not much left at 6.50 m, other than a "typical" semi-detached house floor plan with the only obvious choice: open or closed staircase

He also had the development plan available for viewing during the sales meeting. So he knew the exact data of the property (site plan, etc.) Now huge additional costs come, then credits again, then new cost estimates again, etc., etc..
Just because we are not allowed to build a knee wall of 1.60 after all (which was signed according to the contract) we have now received a credit of €2,000. How can I check here whether this credit is justified?

Take the really good advice from E.Curb to heart and consult a lawyer you trust!

Best regards