Charged for services i did not request

FNB is a great bank, i would never have considered moving, however these recent few months have been just plain painful. I sent an email to my so called banker 11 days ago requesting that they look into the fact that i am being charged for a petrol card that i never requested nor used. This so called banker clearly has no intention of replying since i constantly have to follow up as to what is happening. I mean seriously 11 days ago! nobody has made contact. So what now, must i first throw all my toys out of the cot before someone helps? I want answers FNB answers!