Debitcardauth Nightmare

An amount came off of our account on the 01st of November. We contacted fnb and filled in an outstanding authorisation form. We were advised on the 08th that the dispute was unsuccessful and that we need to submit the cancellation docs from merchant. We emailed the cancellation to fnb on the same day to debitcardauth@fnb and recieved a reply on the 09th of November saying that if the merchant has not refunded by the 16th that fnb will chargeback the amount. I tried sending mails from the 14th of november to the debitcardauth email to enquire if said amount will be reversed on the 16th as the merchant advised refund might only be on the 30th of November. We keep getting mails saying that the mailbox is full and i was thus forced to phone. When i phoned i was advised by premier banker prudence that the debitcardauth division informed her that they still waiting for said cancellation letter we sent on the 08th of November. After being directed to the wrong department i phoned a second time and asked for a manager. He informed me that there is no trace of the email sent by fnb to me on the 09th of November saying that the chargeback would happen on the 16th. I was shunted around from left to right and spent a good 40 minutes on the phone with no answers and no help. I still dont have the answers and as all my mails to debitcardauth gets returned as mailbox full and the manager saying he cant get hold of anyone. This is unacceptable. I have done my part and i expect fnb to do theirs.