Telkom mobile billing complaints!

I am a pensioner, and I am using Telkom mobile for Wifi and I pay a monthly installment not contact but month to month. Telkom has never disclosed to me that if I miss payment on debit date agreed on I’ll be charged a penalty fee of an amount R201 which is ridiculous. I’ve never not followed up with a manual payment cause I can’t afford not to have WiFi. I have never received any correspondence to confirm of being in arrears with my account and apparently this penalty has accumulated to 1500 that they tried to debit from my account this morning. Telkom this is not acceptable, you never send me no email of statement or sms to inform me of penalties or else I would have cancelled this long ago if you guys charge back out penalties for missed payment that I always make sure to pay manually if failed, the banks even don’t charge such penalties. I am definitely opening up a complaints with the ombudsman. I called your customer care line and three times agents call avoided me dropped my line until I requested for a manager who also did not clear explain the amount of 1500