Ok furniture ripped us off # wewantourmoney

We bought a plasma tv Panasonic at Ok furniture Bara mall soweto cash 6500 on the 25 July 2018 , now it doesn't switch on we took it back on the 17 October 2018 they refuse to give our money back or give us a new cause the one they sold us was a demo they took it from the display it's not even three month it doesn't want to switch on today they called and told us the mother board it's damaged . They repair and call us when it's done .what kind of service is this you something cash but when it's broken it's terms and condition but when buy there are no terms and conditions