Very disappointed of FNB ***** department. Cases not resolved and I'm resubmiting of the same issue

It's been over 2 weeks now and my previous issue hasn't been resolved by FNB. They called me twice and told me they're still busy with investigation and till today I haven't been helped. My issue was regard ***** of my account. Money was deducted by online transaction. At the time I didn't even have that money on my account but FNB allowed the transaction to go through and permitted an overdraft. I currently do not even an overdraft on my account so it was really frustrating that they couldn't allow for such thing to happen on my account without my permission. I'm really frustrated and very disappointed.