Unhappy customer - Vodacom

I have on numerous occasions called and sent e-mails advising I am now paying cash each month and no longer on a debit order, yet Vodacom chooses to ignore this and still attempts to put the debit order through. I am getting charged by my bank for a returned debit order and Vodacom charges me R100 each time. For my two contracts. Just a money making business as they do not update their system (due to lack of in-house capabilities). I have logged a complaint and was told this would be escalated, but they do not give me any feedback, apart from calling me and my son's number and harassing us for the monies!! This is not acceptable treatment from Vodacom.......... once again, not a happy customer!!