Vodacom is being *********** and putting me in an unpleasant situation.

I am experiencing a nightmare with Vodacom because of their own mistakes.

I have a cellphone contract account with Vodacom and I have specifically asked them to debit on the 25th of every month for their subscription but they have set for the last day of the month for a debit order without my consent. I've been receiving statements from Vodacom stating that I'm on arrears. I've asked them to rectify their mistake by changing the debit order date to the correct one. But they have never showed any interest in rectifying their own mistake. I've been now and again calling them to help with this situation but they are not interested. I have been very loyal to Vodacom. Paying what is due on time.

Now I have a dilemma of not being able to apply for anything because my name is being damaged becauce of Vodacom and their own negligence. My life is stuck. Please help!!!