Installer installs wrong heating system, offer vs order confirmation

We had some back and forth about which radiators we wanted and ultimately decided on radiators with a flat surface (Model X). We gave the approval for this at the end of May (signed offer with exclusively Model X).

At the end of June, we then had the hydraulic balancing done externally. For this, we requested and also received the order confirmation for the radiators from the installer.

I must have read that. And that is exactly why I asked very carefully. What exactly was done when and how. Title of the respective document. Date. Content (e.g., offer valid for 14 days). Etc. The wording "offer accepted with signature" is not specific. I maintain that your answer is too vague. What kind of order confirmation did you request and why? You do have a contract through an accepted offer — or not? It really depends on the exact wording. Generally speaking: If an offer (not a cost estimate) is accepted, a mutually binding and mandatory contract arises. One-sided changes are not possible. Now it could be that the order confirmation was a supplementary offer from the craftsman, which according to your statement was not accepted by you. Thus, the original contract would stand. In that case, the craftsman would be obliged to fulfill the concluded contract. Layperson’s opinion, not legal advice. My law studies were also too long ago for that…

Here comes an update:

We met again with the installer; he is actually taking back the HK now and ordering the others at the same price as before. Fair gesture, even though he did it reluctantly.