Terminate house construction contract? Wrong advice!?

It is not about "everyone knows that," but about "one informs oneself." I do not rely solely on ONE salesperson's advice for such an investment and believe everything he says right away. That is pure naivety. And as I said, it is USELESS to keep talking and crying about it. The moment has come to devise alternative plans and to plan the next steps. So, no more destructive thinking, but constructive thinking.

Let's come to possible solutions.

Information is still missing as to why the civil engineering is now becoming so expensive. Is it because the plot of land is difficult, or because a civil engineer is charging outrageous prices?
Is there an option to obtain additional quotes from other civil engineers?