Mosaic directing complaints to its distributors is an unfortunate development, but I assume it has to do with the nature of the agreement between them.
I once came across a faulty disc in a Fantasy box set (the Joe Henderson Milestone box, discs mastered by the dreaded ZYX plant). The set was purchased used here in Sweden. After an email to US Fantasy I got a prompt reply: "We have never encountered this problem before, but send us the faulty disc and we'll immediatly mail out a replacement for you". Two weeks later I had a (US manufactured) replacement disc in the mail, and it had apparently been sent out even before my defective disc had reached them. I was impressed with how they handled it.