Rejection fees more than the initial contract sub... Telkom

I had taken a second contract with Telkom, I provided banking details which was not the same banking details I was using for my first contract, I was advised that they will have to use the same bank account that currently reflects on the system to which I agreed and dis kot have an issue, the following month when telkom decides to debit, they debit the account they initially said they can not use and there where no funds in the account. Now I am sitting with my telkom account in arrears, this is not on, they are charging me a rejection fee of R207 which is quite ridiculous ....I will not pay for this, I am also so tired of calling telkom and the agents have lo idea what is going on , you wonder how they are employed to represent such a huge network provider but are illiterate when it comes to basic product knowledge