POOR SERVICE

I HAVE A CONTRACT OF 10GIGS WITH TELKOM, I'M PAYING R199.00 PM VIA A DEBIT ORDER WITH THEM. THE LAST PAYMENT THEY RVD WAS MADE ON THE 1ST OF SEP 2014.AS FROM THE 01ST OF OCT&NOV2014 THE DEBIT ORDER FAILED DUE TO INSUFFICIENT FUND, IN THAT SEND I WAS RVD MY 10GIG ,BUT IN THE MIDDLE OF NOVEMBER I WAS TERMINATED. I RVD THE CALL FROM TELKOM I SPOKE TO THE LADY SAYS I OWE R1400.00 I TOLD HER HOW POSSIBLE IS THAT. YESTERDAY I CALL THEM I SPOKE TO PUMZILE TO PROVIDE ME WITH THE STATEMENT WHICH SHE DID, MY SURPRISE THEY BILL ME R500.00 WHICH I DON'T KNOW HOW DO THEY COME UP WITH THE AMOUNT. WHAT I KNOW I ONLY OWE THEM R398.00 FOR 2MONTHS. I SEND THEM AN EMAIL NO ONE CAME BACK TO ME. I WANT A CLARITY WHO DID THEY ACCUMULATE SUCH AN AMOUNT? OR ITS HOW THEY GAVE THEIR FAMILY AND FRIENDS DATA BUNDLE AND BILL US AFTERWARDS.