Terrible service that's costing me money I do not have

In April 2015 I visited FNB Carlswold to downgrade and freeze my account as I can no longer afford the monthly fees. The guy who helped me assured me that it is done. I specifically asked for a confimation paper or letter but he said no need as I will not need it. FNB has always given me great service and I never had an issue with them, so I trusted him. This morning I go to the Garankuwa branch to be told that I no longer have an FNB account and I owe the bank R 270! No notification! Nothing! The lady who was helping me said there are no remarks on showing I ever asked for a downgrade!!!