Charged rejection fee for debit on incorrect date and redebited

Telkom debited me on the 24th of November when my debit date is the 25th of the month. I phoned the call centre they said because it fell on a Saturday that happen but i have this contract more than 26 months they always debited on the 25th even if it was a Saturday. Its been 2 weeks I even got a case number no response but then on the 30th i get debited and still get charged R200 rejection fee which is not my fault.