MTN ruining my life!

I had a data sim contract with MTN, when the contract ended I phoned in to cancel but decided to take another sim but informed the sales person Carem ( who also worked in retention department). I told her I’d need a new sim as I lost the other one. The new sim was never delivered to me and I decided to call in again. I asked for Carem and shared with her that I would rather want to cancel everything and cancel the old contract. She assured me numerous times that the contract is closed. A few months later I realised that I have an arrears account at MTN. After investigating I realised it’s the initial contract I had that was never cancelled. I phoned in and even spoke to Carem’s supervisor and Carem also phone me to ask what the problem is but it was never resolved and no one ever came back to me. I went to legal aid and they advised me to pay in order to get a paid up letter as proof this time around. I did just that and after a long struggle I got a paid up letter. Now I am trying to buy a house and will be unsuccessful until MtN is from my name and I WILL NOT PAY THEM R10 000 after paying them R5000 ( which I think they need to repay) for they made a mistake and their staff is shady and ***********!!!!! MTN will never get me as a client again and I am actively discouraging another to either leave them as a network or never even approach them for any business!!!! MTN is ruining my life!!! I can’t own property due to their incompetence and *****ing from people who are already struggling in the economy and times!!! Shame on MTN!!