Wonder Park cash crusaders

I bought a Bluetooth speaker at the Wonderpark store Pretoria on 18 April 2016 and I was not happy with its battery performance and overall sound performance and on Monday 20 April i took it back ,the store is refusing to refund or exchange it claiming the only assist if goods are faulty. This is a clear contravention of the consumer act because it's still within 7 days and I have the original slip and packaging I bought from cash crusaders because i thought it's reputable store that protects its customer rights but clearly i was wrong and also the store manager was rude and condescending.