Complain

I bought earrings on the 26th if December 2023 at American Swiss Rosebank then when I got home I realized that the back part is loose then I wet to American Swiss highveld mall Witbank to explain my problem because I stay there one of the cashier told me there's nothing they can do about it I just have to keep those earings because is not their fault. Then I went back home after a month one earing fell because the back part is loose and this earings are expensive they gave me the same attitude which is bad attitude they didn't even bother to give me advice the only thing they say is there's nothing they can do is not their problems so I need help I am not happy at all.