Cheque account and additional chargers

My FNB cheque account has been charged interest for debit orders I had not authorised to debit my account and FNB has now defaulted my name at the Transunion. In January 2013 I was contact by lady named Semakaleng Ramela from Premier Resolution Centre following my complaint on Hello Peter on this matter. She then assisted my by send a Dispute Debit order form that I had to declare and sign regarding the debit orders. Semakaleng Ramela only managed to reverse 4 transactions but I had counted 10 that needed to be reversed. I then send a email to her on the 30/01/2013 and she didnt reply my email about this matter or explain why. Today the 29/01/2015 I call Rachael Pillay from FNB Value Banking Solutions who assisted me with bad attitude and didn't give me a chance to explain my situation. She later sent me an email with my bank statements not explain to me how the balance accumulated and request me to contact debt collector REVCO to discuss a re-payment arrangement. My question is how do I call the debt collector and arrange for something I have despite on. This is not suitable as this is my second complaint about FNB and trying to make money out of me.