Poor Debit Order Service

I have a problem with Telkom and its for the second time, Last time I phoned to change My banking details to another account and advised they should continue debit the money on the current account then on the following month they can debit on the new account number, and that was not done instead a new account was used to debit the money and funds were not available i had to go and do the manual payment. now same thing has happened I told Telkom to debit money on the 20th of Every month but instead they went to my account on the 19th to debit the money living me with unpaid services and charges giving my bank account a minus, so tell me why is your service poor? what must happen to the charges that I've received or must I buy out the contract and move to other network? I need an explanation and those fees must be payed back, Your Service is just worse than drain.