Reverse my money

I just want to understand what's the purpose of debicheck if Fnb is gonna allow debit orders on my account to go through without being debicheck by myself, now telkom who have no business debiting my account have debited my account and I can't dispute it, I saw they tried this before and I went to secure chat,and the reply came back hours when I was nolonger, dear Fnb please reverse my money and block future transactions from telkom and any transactions i didn't debicheck, or I swear next months I am moving my services to capitec, if you can't protect my money as your customer,now I am even posting in hellopeter not because I want to, I have no choice but it's the only way I will get help I want my money back and telkom blocked from future transactions from account