Over debiting

Around June 2017 was contacted by Mondo and they offered me a Telkom starter pack was paying R117 per month, for two years (24month) the service was good. After 24 month it now became a mission to cancel the deal, the card was stopped but till to date Telkom is still taking money from my account for the service that I do not have. Can some one kindly assist me in this matter Thokozani Ngubane ***