Sterns disappointing service!!!

I am very disappointed and upset with Sterns because I now am sitting with a ring which was purchased on the 25th of September 2025 and its of no use because I get a very bad allergic reaction everytime I put it on. I went to Sterns east rand mall today, after reading the T and C's at the back of my slip and says that there is a 6 months return policy should anything have any defects. The lady at the store told me that an exchange nor a refund is possible and that I should TRY sell it at Cash Converters which I find absolutely absurd because I do not want to sell a brand new ring, I opted for a refund because apparently I can't exchange nor refund. I have my slip and packaging so I don't see what the problem is!!!!