The company called Coasair told so much lies to their customers. Ruled by your law? Or that's what you Americans do?

The company called Coasair from C.A. sold so many stuff everywhere. When the stuff from them doen't work anymore I asked them for an RMA process as it's still in warranty. However, all they did is just shitting me. They asked me to ship the defective goods back but not ship me back a replacement. After I called them they said that's their fault and will upgrage the prodct to me. However, they didn't ship the stuff to me, let alone following their commitment upgrading. Is that the rule of American companies? Is that ruled by your law? If not, please rule your companies following their commitment.