TELKOM CONTRACT UPGRADE

I have upgraded my Telkom line requested to use my old number. My line stopped working when I phone for assistant, Technician tried to activate Sim card with no luck then refered to the shop. I went to eastrand mall telkom shop then they said I must wait for few days Sim is still transitioning. It is full two weeks today with no service and when I phone they refer me to different service line no one is willing to help me. I am sure they will deduct my account for service I am not using. I currently buying air time and data cash. Pls help to cancel the contract. I do not want to be blacklisted for this.