American Swiss review: Inferior products

I am a tfg customer since 1998. I have always purchased my jewellry from American Swiss including our marriage Jewellry. Last year 2023 Oct I purchased 9ct gold sleeper earrings for my daughter. In Dec 2023 I noticed that my daughters earrings had turned colour a bronze colour. I took the earrings back to Blue Route Mall American Swiss where I was told by a manageress that I could have the product returned and swapped for another pair of earrings. We left to fetch our sale slip and returned 2 days later to swap the product. There were other sale persons in store whom immediately retaliated negatively and stated that we could not change the earrings. They also stated that 9ct gold would never change colour and maybe we had 5ct earrings. But how is this possible if our slip proved that we had paid for 9ct gold. This could only mean that the American Swiss store sold us inferior products for elated prices. The original manageress was very quick to reimburse our purchase afterwards regardless of what was stated by the sales assistants. Something sounds fishy and needs investigation. Are we customers being duped into buying inferior products at elated prices. Who is quality checking this organisation'and are they also accountable for what is happening here. To add to all the drama, I lost out on my tfg rewards which I originally used when purchasing the earrings. What ombudsman is related here.