Pep Is bad at customer service and don't listen to me

My mother bought me amplify vice Bluetooth earphones on the 04 / 09 /2024 when I got the earphones It the one earphone only played once till the battery died, the other one works fine, so two or three days after I told my sister to take it back for me and I explained to her, I charge both overnight and then it shows it fully charged but the one still dont go on, so my sister took it back but then they told her at PEP that there is nothing wrong with it, and now she don't want to take it back cause she says she don't wanna look stupid, all I can say is I paid a whole R150 rand just to buy broken earphones and then I get told that there's nothing wrong, I know when somethings wrong because I work with electronics stuff, PEP is really giving bad service and I would like to take things further, because I've never experienced an situation like this