Obsurd billing

I am not sure how am I being billed but i really dont understand what am i charged for. Past 2 months for some unknown reason im told i have a balance(brought forward) I had alerted you that i am no longer working(retrenched), and therefore request that im billed on the 5th, which means due on the 5th Sept was R743. Somehow on the 26th Aug, multichoice debited n there was no money. Then the 29th i paid R500, and the 2nd Sept i paid R300, and emailed both proof of payments. To my suprise today, on dstv app my bill is R907 how is this even possible from my poor mathematics R743-R800=-R57.Can someone care to explain what are you billing me for?