fixed price guarantee

these clauses and subsequent price increases are at least inadmissible in the way they are carried out.

Which way does she mean? The flat-rate price increase? And which way would be legitimate? Probably the way that is openly disclosed. I would be curious whether that wouldn’t then become even more expensive for you if the house price is recalculated. I have to admit, I also see it rather critically. Any price increase has to be questioned, whether with you or elsewhere. Also the contract. Above all: are price increases avoidable, what is the cause behind them, and so on. Only if you as the client are already the reason for the delay, where should checking documents and lawsuits lead? To wrongdoing?! In the end, you signed… Or rather to irrationality. No hand has been laid by the contractors yet, and you want to sue your partners_o What would be the conclusion or could the consequence be? The contractors delay themselves and then sue you? :p