MTN Ferndale on Republic ****

Whatever you do when cancelling a contract do not return your WiFi router to MTN at Ferndale on Republic, 3 months after cancelling I keep getting debited R2230 because they claim I did not return my router. I signed papers and spent almost an hour in the store because of that but somehow the people who helped me did not return the router as when I call MTN they acknowledge I did cancel but that there is no record of me returning the router