Worst service and responce

I had two contracts with MTN and I went to cancel the one as the 2 year period was over and I was no longer using it. They never cancelled it and I was billed for it every month for about 8 months before someone at head office got that one cancelled and the money refunded on my account. As this process took place my other contract was blocked because I refused to pay for the other phone which I cancelled. I told them I am not going to pay for something I can not use because the people at the store didn't do their work properly by cancelling my other contract when I paid the cancellation fee and filled in all the forms. Apparently the store in Stellenbosch was taken over by someone else so my cancellation papers got lost in the process and they never cancelled my contract. The other day I found out that there is a judgement against my name because of MTN personnel not doing their work properly. I want this judgement removed from my name and my account settled and closed. I am not going to pay for something I couldn't use because of the negligence of your staff. My account is in arrears because it took MTN's staff longer than 8 months to sort this out. What will be done about this?