FOREX charges not planned for

I made a forex payment in August and the charges were just processed now in December on my account without receiving any notification ahead of the transaction being processed. My account is now overdrawn as a result of this transaction and I hope that FNB will not be holding this against me by recording this or charging my account with penalties. Surely the FOREX department should put a notification system in place to advise clients about pending bank charges? I gave a Good rating as I know the problem solvers at FNB always deal well with the queries that arise from some FNB departments that really do not care about customer service.