Unauthorised deductions

I have a legal contract with clientele life insurance that specify that they should deduct on my account on the Th and if it's a weekend Friday before the weekends, but now it's the opposite, I am now been billed on the 15th which have made absa deduct more R400 for insufficient funds now my problem is since now I have a black and white contract who will now refund me because Absa it's not at fault and I'm not on default. Clientele I would like a refund for an automatic deduction that was not authorised by me. This is poor administration and not following instructions of what you draw out to be supposing to be following.