Worst service from Fnb fleet card division

I am a shareholder in a petrol station. FNB fleet card division queried a transaction via email. We did respond timeously, as there was a perfect explanation for this transaction and it was not *****ulent. They never even bothered to respond. I send a second mail, yet no response. Fnb then went ahead and deducted that amount from my bank account, incorrectly so. I tried to resolve this matter via email, no luck. Tried calling numerous times. No luck. This is just terrible service.