Stop debiting the wrong account seriously ,telkom is a *******

can telkom stop debiting my account for money that is not there , i gave you my new bank details yet you continue to debit from my old account which in turn causes that the bank charges me R100 for an unpaid item and telkom has the nerve to charge R202 per unpaid item which now shows i owe telkom R404 plus my monthly subscription , you guys are pathetic ,i cannot wait to pay off this contract ,i will never do business with telkom agaian