Update. Have just returned the boards to the mill and got our money back. Taxi fees will be our loss though (those boards were heavy), but at least I have something to spend towards better quality shelves for the cats.
- Looking for inexpensive untreated / pet-safely treated wooden board for indoor use; suggestions very welcome!
Well, since sawmill saw it fit to sell us those boards for the specific purposes and uses given to them, I felt cheated.