Defective Stock & Bad Service

I purchased a gold&silver band for my husband for Christmas around 18 Dec 2017 before flying overseas for the holidays. I gave him the ring for Christmas but it didnt fit so we put it back in the box, intending to resize once we returned home. When we got home and opened the box the ring had turned black.

We took the ring back to where it was purchased (NWJ Mall of Africa) where I was told they only do returns within 10 days. When I showed the "manager" the slip said defected items can be returned within 6 months she said the salesperson should have written on the slip that it was a gift. 1. obviously a woman buying a mans ring is a gift. 2. it doesnt matter whether its a gift or not, supposedly gold and silver should NOT turn Black! All the women could say was its not her problem, she doesnt 'fight' with customers and we know how our 'people' are referring to our race. We hadnt fought with her or even been difficult. And this is a "manager" She said she would send the ring to head office because they dont do refunds. Still awaiting a response. She then told us the ring was from the cheap range for people who cant afford full gold rings. I purchased that specific ring because it looked like one that had been ******, not because it was cheap.

And why would I want an exchange for another piece of jewellery that turns black?