Dear Hansi, you have gotten a real specialist :( I am sorry for you! I still maintain the opinion that every client should research in advance what a house costs. No matter who promises to build the house for 150k, they will fail. Even an architect can / may / must be questioned. You did not agree on a fixed price, but the architect had calculated construction costs for you in advance - that is something completely different. It is also somewhat naive to now place the entire responsibility on the architect. The soil report can also be explained by the producer of the report, then you know what to expect. In all lists by building experts, additional costs due to foundation are included. Exactly for such cases. Ancillary building costs are also very well documented here in the forum - read through the various topics about this and you will realize that there can still be many pitfalls. The architect must have submitted a deviation analysis for each trade compared to the forecasted costs, right? Or you didn't do that yourselves? If that is the case, the first contract should not have been awarded.