Billed for something I did not sign up for

This is a formal complain against telkom maponya mall. I was assisted by a very *********** lady Nomthandazo who i intially needed assistance with upgrading of a contract she gave me a sim card with another number which i asked her why because i still have the old one,she told me its a new process, then she told me the sim card will revert to my old numbers after 24 hours very strange because I've done some many upgrades. After 24 hours i called my number was still not back she and her manager promised i will not be billed for the number they gave me now im being billed R600 for the number they forcefully gave me. I need to be reimbursed or else im taking this further