Charged extra for a change in billing cycle that I did not authorise

Charged me R566 extra on my monthly bill for November. When i enquired, I'm told that its due to a bill cycle change which I did not know about or consent to. I should now be charged less for the next month but when i get my new invoice for December, I am charged the original amount again, no deduction of the R566. I query this again and they close my request.

I demand a refund of the R566 that I was charged extra for the billing cycle that I did not authorise. This is an official complaint, I will be going to the ombud if this is not resolved.