Diplorable MTN

Two of my contracts with MTN expired in August of last year. I called in to say I would like these contracts cancelled and converted to prepaid lines (there is a recording to prove this). Needless to say the lines were not canclled and I was charged, and the lines were then disconnected. I have called in so many times, have endless reference numbers, with promises that the charges would be reversed, and the "supervisor would call me", all empty. I'm still being charged, with no feedback at all from MTN.