Terrible Experience with Revolving Loan Facility

Terrible Experience with Revolving Loan Facility department, I was given so much of a run around and a couple of days later still no feedback or assistance, it all started when a FNB staff member offered me insurance on my revolving loan facility, I accepted it and all went well, till my debit order had to go through, the debit order for the insurance went of, but not for the monthly insurance I had to pay it manually, the second month the I received a reminder that my installment amount was due by the 28th, on the 26th I paid my installment with a few rands extra, but it was not seen as a payment, and now im getting messages that my account is in arrears i called FNB spoke to few different people, the advice that they had to sent an email to the maintenance department, and still today no feedback was received, i got a message the weekend again that my account is in arrears and this really affect my credit score. I don't know who else to contact because there is no direct contact with the maintenance department, and the consultants that answer the phone don't have no authority to assist a person with just a simple problem like this