HORRIBLE HORRIBLE HORRIBLE

So my father and I signed up for an internet contract with MTN. I specifically told her i needed a sim card that would go into my phone since.. She confirmed that the deal was sim only and would work on my phone. However when I got home I had 0 connectivity. I told her I needed to cancel the deal asap and she asked me to return the sim and she would cancel the deal. the following day I took the sim card back and the agents there had a discussion about taking it back which they did and the following day my father received an sms that the contract was cancelled. we then signed up for another deal with supersonic and every single month since September there have been deductions. We found out last month that it was the initial MTN contract that has been deducting and now we owe R9000 toward supersonic . Spoke to your team last month and they promised that they would have cancelled by now and yet there was still a deduction. disheartening because I practically begged my father to use MTN because they were reliable and now this?