Block Account

I had it with game its the worst service I ever had, I WANT TO BLOCK MY CARD!!!! EVERY MONTH THEY TELL ME ITS ANOTHER R100 ANOTHER R30 THEN I PAY IT, WHEN I GET MY STATEMENT MORE MONEY NEED TO BE PAYED!!! MY SETTLEMENT IS PAYED PLEASE I DONT WANT TO PAY ANYTHING ANYMORE. Please block my card. Regards Chenene