unauthorised debit orders! STAN EXEC S/C CHARGE

I have been trying to query an unauthorised debit order on my FNB account, that it seems was placed there by Standard bank for R171.00 with the description "STAN EXEC S/C CHARGE". Every single person that I have spoken to at FNB's call centre has been completely useless at helping me, and keeps on transferring me to another department. And half the time the call is "dropped" as they transfer me, I suspect they just end the call out of rudeness. I need someone to contact me urgently.