DSTV double charging

Good day, I have DSTV Compact. I pay my account on the 25th of every month. But on the 6th of every month DSTV decides to cut of my subscription and after many fights one of tge consultants told us its because we don't pay it on the 6th. So now i pose the question how is it possible that we can pay the full amount on the 25th.... 11 days before due... And then they cut us off and we need to pay AGAIN on the 6th... Twice for one months subscription???