Wrong debit

I have requested that mu debit order be moved to the last day of the month, however Telkom decided to still trey and debit my account on the 25th. I paid them online on the 27th and then they try to debit my account again on the 29th. In the meantime I have to pay the fines for insufficient funds on my bank account. Now Telkom will add an additional fine of about R200 on my Telkom bill for debit order reversal. I have lost my job a year ago and it has been an uphill battle all the way but managed to pay my account with Telkom. I just can not afford it to keep paying fines upon fines every month with the little money I do get in. Telkom please get you act together. I have been a loyal customer for 15+ years.