CNAC Sal... Account Manager Withdrew Money out of my account Internet

 sounds like the same bs again

At one time in the past, you made a payment on line and checked the ONE TIME only authorization box for that payment and that payment alone.  As per your understanding of that process, you authorized them to take out of your bank account one payment and one payment only.  Now we come to today and they took another payment from your bank account, thus causing an overdraft.  Here is what you are up against...you need to go into their website to read exactly what it says regarding your giving authorization for ONE TIME ONLY.  There are terms and conditions regarding this.  It could be you agreed to terms such as "we will withdraw from your bank account only once.  However, if any payment appears it will be late, then we will withdraw from that same account again."  Again, what will govern this is what the terms and conditions say.  Next, I would go to your bank to find out if that one time authorization actually was a one time only authorization or a blanket authorization.  At any rate, if all is what you say it is, this sounds like a fairly interesting case!