Incorrect billing scheme vs system issue

DSTV has debited incorrect subscription fees on my account for the past two months, each month I have logged a query that has been "escalated" to nowhere it appears, when I call to follow up, they cannot find the case number references and I have to explain each time to a different consultant what my issue is.

That I have authorised only the price-lock amount to be debited from my account and DSTV is taking liberties by continuing to debit more money. The failure to resolve this issue in a timeous manner but to continue taking more premiums seems to me more like DSTV making money at my expense. I cannot be expected to call in each month only for DSTV to take money at their discretion and object to my request to change my payment method to pay via the alternative payment methods available. Clearly DSTV is not concerned with getting what is due to them but abusing the debit orders for its convenience.

I just want a refund, for you to bill me correctly for the remainder of the price-lock period and to cancel at the end of the period because I do not want to deal with this problem for another month.