Incorrect bank charges

I have a terrible experience where I was charged a R1000 bank charge for supposed transactions FNB honored. I've been with this bank for years, but recently reopened my account in Nov 2017. I spoke to am agent who said he couldn't see such activity on my account and would send a request to pricing to reverse. He told me it would take 24 hours. I called after 24 hours and another agent says it takes 48 hours. How can two agents working for the same bank give conflicting information. And how can pricing make such a mistake. How many other people are being priced incorrectly??? This is very concerning. For a world class bank to make such an error. Now I'm out of pocket my account is in minus coz if someone's error. Can this be fixed immediately please!!!!!!!