Construction company halts work despite overpayment

I will try to explain. Mr. T.... belongs to Wxx. He is the intermediary. We received the offers and the contract from Mr. T. The construction contract was signed by Mr. T. as intermediary and Mr. Z. as contractor as well as, of course, us as client. Before that, we had nothing to do with Mr. Z., only at the time of contract signing. Mr. Z. is managing director of Z.Bauunternehmung GmbH.

: This is not stated in our construction service description.

Hello, how many square meters are we talking about here? This seems to be a tightly calculated price, even in the East. Earthworks are usually not included.

Reference is made to Appendix 1. What does it say there?

: This is not stated in our scope of construction services.

If this is supposed to be a scope of construction services for you, everything is clear to me...

Well, if everything is clear to you. You are probably the only one. The fact is that there is a signed construction contract that both parties must adhere to. And it does not say anything about additional costs for structural reasons. Annex 1 contains our additional requests. The disposal of the soil was invoiced separately, by the way.