Over billed

i received my statement for august yesterday and to my surprise i owe R500.4. I called the call center and i was advised that i didnt pay the account , they went into my account on the 24/08/2018 and the debit order bounced back - I explained to the consultant that my debit order is the 25 not 24 and telkom did debit the money on the 28/08/2018 . i was told that the debt collection debited my account on the 28/08/2018 and i still need to pay R200 for the fact that the debit order bounced back - why should i pay the subscription fee of R200 while money was taken from my account and i never said they must debit on the 24/08/2018 - i request copy of the recordings and contract where it confirms my debit date or if i was told that they can debit any time and i agreed ,