Handed over...for a non existant contract

I honestly feel MTN are infact the worse service provider in SA . Last year I cancelled my 3g contract ( it was already on month to month ) I was told after that months debit order had run that would be that. However the month after a debt was processed for three times the monthly amount and again another month was processed , so I had the debit orders reversed and. I never heard from MTN again. Fast forward 6 months I am applying for credit and find out that I have in fact been handed over by MTN ( I never had a call or any correspondence ). After several attempts to get hold of someone who could actually help I was told the legal manager does not take calls , so I left a message and still have not a call back . I need this resolved urgently and will take my own legal action if required. Please be very careful in your dealings with this establishment