I work at a retailer that sells flooring, i can say from experience that all the money issues should have been delt with prior to the installer's coming over as this seems to be the brunt of the drama.
Laminate will scratch yes but not easily, even the cheap stuff will not scratch easily, you have to keep in mind that pets with claws not trimmed will not scratch laminate.
I see you mentioned that the installer said that it will scratch if you move furniture across it, all you simply have to do is get some felt pads or pads that go on the bottom of furniture, you can buy them at home depot, PROBLEM SOLVED LOL.
It sounds like he said that just to irk you, dont be irk'd your flooring is fine.
Im sorry to hear that you got poor customer service, youll probably be better off next time if you use your local home depot or "lowes".