Telkom weak security causing me money

Telkom has weak security or I’m being ****med by someone working at Telkom. They debit from my account anytime the feel like it and when they don’t get funds, I must bare the banking costs. It’s not the first time this is happening with me with Telkom. I’ve been with Telkom for more than 12 years but their security just gets weaker. On my statement it shows that I’m behind every month while I’m not. I can’t wait to finish the contacts I have with Telkom to never renew with them again coz it’s clear that my bank account is not safe with Telkom. I’ve cancelled a lot of debit orders with them so I can pay manually to feel safe but they always find a way back to my bank account. I can’t wait to be done with telkom so I can get rid of these unnecessary costs they’re making me pay.