Unfairly overcharged by Telkom Mobile

I have never experienced such appalling service in my life, Telkom stole my money. My debit order, which I have never missed for over 2 years is R698.04 was increased to R884.04 only because for the month of August, I made a manual(EFT) payment because I knew there won't be funds in my account since I'm no longer employed. I paid on the 24th of August because my D/O is on the 25th of month and they received their funds on the 25th. To my dismay I was told I get charged like R200 for paying manually instead of a debit order, I was so shocked because, 1 I didn't know of this and regardless of my employment status, I still honoured my contract with them and paid. I spoke to numerous agents, 1 of which promised me he will waiver the charge as I wasn't aware of this. They debited my account this month with an extra R200 and they refused to refund my money.