Telkom Charges on a non arrear account

My telkom account is in arrears for more than R500 already because telkom doesnt have the facility to deduct their installment on the 31st from my bank account..... so they charge me a penalty fee. They receive their installment every month on the 25th through a manual payment. Yet they penalise me because they are unable to service a client on their required need. If telkom doesnt have the facility to cater for the debit order to go off my bank account and i make an eft payment before the due date HOW CAN I BE CHARGED A PENALTY?????? I NEED AN ANSWER ON THIS BECAUSE THIS IS REDICULOUS.