Poorly designed jewelry

I bought a S pendant infinity series a few years ago. Dec2022 I upgraded it to the biggest S pendant they offered. The pendant lasted only a few weeks before the chain started to cut into the connector loop. It took them 6 months to get it repaired after lots of deliberation over payment. The replacement unit came with and even small connector loop which allowed the chain to cut into the loop within 1 week. Browns say I am the only client with this problem. I questioned I am the only client who has the pendant on 24/7 - who else uses the pendant all the time, their other clients keep them locked away in the safe. Anyway they now charge me R1700 to repair it. The fact that the heavy pendant is not made to hold-up such big diamonds with such a thin chain the caius cutting into the loops they refused to admit it is poorly designed. Who would think a complaint would exist that my diamond pendant it too heavy and the necklace chain is cutting into to loops. Seems like a problem for wealthy people. Whatever, the problem still exists and they refuse to do anything to rectify the problem