Products that will always Break and cannot be repaired

I bought a pair of 9ct gold earrings on 12-10-2017. Less than 1 month later both earning broke and I returned them for repairs to NWJ. I was charged for this repair. I even offered a piece of my own gold to strengthen the areas where they broke. After another month one of the earrings broke again, even with extra gold for extra strength. This time NWJ did the repair at no charge. One month later the other earing also broke, but this time (04-02-2017) I was told by the shop manageress in Cape Gate, Harrie Tlestrade, that these earrings will always break as the gold is very thin (even with the added gold I provided). I asked for a refund or replacement as this is clearly a defective design. However Harrie told its no possible as there is a 10 days policy and no refund for earrings. I showed her on the rear side of the till slip the written policy being 6 month for Defective Jewelery, but she insisted these earrings are not Defective. Yet Harrie acknowledged the earrings will always break no matter how many times repaired. Surely by reason of common sense this was an admission that the earrings were defective. Why sell products that will always break and cannot be repaired? I want my money back including cost of my gold provided to them! Julia de Beer.