We Will Not Change Your Debit Order

So after trying to contact that accounts department in order to change my debit order details I was unsuccessful, I was left to fill in the online form to be called back, there was just no call ever made to me in order to do so, guess what therefore happens, I get debited on the incorrect day and get charged for it by my bank, in addition to this my services are not paid for, please can this be changed and my unpaid debit fee returned thank you, much appreciated, PS: guess who is not renewing his contract with Vodacom.