DSTV incorrectly billing continuously

Every single month i need to call in to ask call centre to correct my bill. And every month i am promised that it has been sorted, but its never the case. My bill is R899 per month, i am charged between R1000 and R1300, where DSTV gets prices is anyones guess. I have just cancelled my subscription.

Smart card number - 1 ********** 033