Not happy at all with rain service. How do i get my money back??????

I am very angry and disappointed with their service. I app**** for the device paid R699 they delivered it after 3 days and activated my simcard bt it never worked... They kept on saying i must switch it on off bt it never worked. Final after a week they came n collected my device and they promised tge refund between 7 to 14 days and nothing has happened. End of the month they deducted onother payments of which i dont understand why would they do that if im waiting for my refund from first payment. I need assistance not happy at all about their service they need to do something.