Failure to close account after by consultants

Around last year July 2014 i closed my account with FNB and switched to Standard Bank and because of poor service and transactions going off my platinum account which FNB an't even confirm for me. I had nothing overdue on my account and also switched all my debit order and stopped them with FNB. Now more than a year later a receive emails which states my FNB account is overdue with around R6k, i closed the account at the FNB Centurion branch and my salary was paid into the Standard bank account from there on, i tried calling them to fing out how the Hell is this possible but they said the account wasn't closed according to them. And they can't put me through to a manager or so. People don't know what they are doing and they can't even close and account after confirming when i went to the branch to close it that it was closed in fact.<br> This is unacceptable and i will not pay for a mistake they made on their side, hope FNB will come to their senses and sort this out.