wrong debit order date and charges

on the 31 March 2019 I took out a contract with Telkom for a router and two cellphones. My payslip and bank statement clearly state that I get paid on the 25th of each month. I told the guy at the store that my debit order should be on the 25th of each month. I don't know what happened but my debit order went off only on the 5th and it bounced as I had no funds in my account. I made an EFT to sort everything out and paid bank charges for the bounced debit order. to my surprise this morning I receive my statement and telkom is charging me R200+ for the rejection from the bank and I was not at fault. I was not the one who entered the information incorrectly and refuse to waste money on charges that could have been prevent had someone done their job correctly. I want telkom to reverse those charges or else cancel my contract.