Being over billed

Since 2019 September I have been over billed from dstv I have made so many call emails did just about anything to explain that I am being over billed in December 2019 in all due respect after complaining for over 4mths I did get sum of my money back in credit but as of this year 2020 for a price lock plan which I am on in was to be paying R550 p/m I am once again being over billed the bill for the mth of January is R700 which is not the correct amount can any1 for dstv please assist me with this over billing problem