REFUSAL TO DEBIT PRO-RATA (END OF CONTRACT)

MY CONTRACT EXPIRES 02.02.2016 BUT VODACOM INSISTS TO DEDUCT THE FULL AMOUNT FOR AN ENTIRE MONTH ON 01.02.2016. THEY ARE NOT PREPARED TO DEBIT ONLY A PRO-RATA AMOUNT FROM MY ACCOUNT, NEITHER ARE THEY PREPARED TO SHIFT THE END OF CONTRACT DATE 2 DAYS PRIOR TO THE EXISTING EXPIRY DATE. IN OTHER WORDS THEY WANT TO FORCE ME TO PAY A FULL MONTH AFTER EXPIRATION DATE OF MY CONTRACT AND ARE ONLY WILLING TO PUT ME ON PRE-PAID END OF FEB. I'M VERY UPSET BY THIS AS I'VE SENT EMAILS 3 AND 2 AND 1 MONTH IN ADVANCE TO HAVE MY CONTRACT CANCELLED BY END OF JAN. I HAD TO PAY R1800 CASH FOR FEB!! WILL NEVER TAKE OUT A CONTRACT WITH VODACOM AGAIN