Worst customer services

I bought a phone at PEP cell and it was giving me problems, it switches off when in use and some times it freezes, when I went back to inform them about the problem they were very rude the name of the cashier is Sanelisiwe, the PEP store is along Eloff street in Johannesburg, she told me that they can not assist me because they haven't seen the problem it did not happen inside the shop.