This sort of thing can work both ways.
A number of years ago, I was on vacation and bought an instrumental jazz CD. I didn't open it to play it until I was home, and another CD was inside the case - a CD by female vocalist. I had no idea what the name of the store I bought it from was, so I took a chance and returned it to the manufacturer (BN/EMI). They replaced it within a week.
IMO, if the manufacturer screwed up, and the buyer goes back to them first, the manufacturer should make good on whatever needs to be done. If the buyer goes to the supplier first, the supplier should make good.