I am really tired of vodacom

In February i did a review i did a review on this site because vodacom conveniently decided to change the terms of my contract , changing my debit order date or changing my payment method. They did this without informing me or my consent. On my contract i agreed that they will take a debit order on the first of each month. So if you decide to change things & do things that are outside the contract of what i agreed on. Why must i suffer for your incompetence. Now I only get contacted with you guys that i must pay this huge amount. I won't pay this amount unless I get somewhere on my contract where I said something different about my method of payment or even a voice recording where i changed my original method of payment which is different from what i mentioned above. I though this matter was resolved , when i spoke with you guys in February this year. I wonder whats so difficult about doing exactly what i agreed my payment method was & when to debit. We wouldn't be in this predicament had you done exactly what I agreed on.