Paying For A Contract That was Cancelled

Took a contract on sony experia Z2 which had a fault on speaker. Took the phone back to the mall@reds branch before 7 days but they wanted to charge me a cancellation fee? why? i dont know cos i was returning product before 7 days which is within my consumer rights.Spent a whole day at the branch but the staff could not help me or resolve the issue. After numerous calls the manager calls to say that she will swop the phone for a Note 4 which then was *******ly changed on a contract on my name. I have not received the note4 or signed for the contract but am paying the bill for it for the last 5 months.I have now contacted telkom customer care who supposed to call me back this morning but i am still waiting.....