URGENT: MTN is ruining my credit record, unfairly!

I took out a 24 month contract with MTN on the 7th of February 2013, which was officially activated on the 17th of the same month in 2013. This contract expired, this year in February. I then went into an MTN store (Centurion Mall) to request cancellation of my contract. I was informed that I had already been billed for the month of March and that I need to pay that instalment, which I did. Later on I learnt that my account with MTN was still active and that I needed to call the call centre as most MTN stores were unable to assist, in particular the store at Wonderpark mall. I then tried to call the customer care line ample times, with no success. I then went into another MTN store (Menlynpark) where I queued for over an hour and eventually left when the shop closed without getting assistance. I resorted to 'twiter' as I was told that MTN does respond to 'tweets' almost immediately. To this day, MTN bills me for a contract that not only expired and that I requested cancellation of, but that they blocked. I eventually got through to the call centre and relayed my story, on two occasions, I was told that MTN would revert with a possible solution. <br> <br> <br> This is really messing up my life!