Account not debited.

My account was not debited and no form of communication was made to me as to why this happened. I received my April invoice and it was a ridiculous amount, when I called to asked them why my account was debited, they told me that I was meant to do a manual payment. When I informed them that I was not notified of this, all they said is “sorry”. I do not understand why Telkom’s negligence is now my problem cause they are now telling me that I have to pay the full amount or make the manual payment and I do not have the money, as I never use all money up until the 2nd of every month, because my debit orders are all out by then