Problems with the bathroom builder before work.

Offers and invoices are typically created with the same tool nowadays. That means if the offer is already so unqualified, the invoice will be just as careless later on. If you still want to use this provider, I would have them note on the offer: "the materials used correspond to the parts list in appendix A", meaning you then attach your shopping list and they sign and stamp it. Or not – then the order goes elsewhere.

That's why I need exactly this list first.

Now I'm completely confused. I thought I understood that this list was compiled by you, that is the sum of your sampling activities (?)

So I fear it comes down to you having to do it again and then write it down yourself – otherwise the bathroom builder (formally "rightly") will install "something or equivalent."

Why do you sample without documenting "what"? – I only know it with a smartphone, "click" on the tile, "click" on the price tag with the model designation ...

Because the exhibition neither displays product names nor prices, but one goes through it with a consultant, who takes notes and passes them on to the craftsman, who then buys from him.