Selling stylo tablet that are not functioning and refusing to refund me my money pep fourways

Good day please kindly assist I purchased a tablet at fourways mall pep next to game . 2 tablets. The other tablet was not working for the first 6 days the battery would say it's fully charged and after it goes back to 0 % . I went to mall of Africa Pep to change the phone or to get my money they advised that they will give me the another stylo tablet which was even worse than before and today when my husband went to pep fourways to let them know what happening they said that it's been over 7 days they can't refund me for the other tablet yet they keep on giving us tablets that have issues, I no longer want that tablets I rather have my money back because my child is using the tablets for school now she is left behind,they took the tablets refusing to give my money back saying they will keep it for 3 weeks I no longer need that tablets all i need is my hard end money , and why would they keep selling the tables that don't even function properly please urgently attend to this matter I cannot stress enough about my money that i worked hard for and to be sold something that doesn't even function