Product: Checking or savings account

On or around XX/XX/XXXX, I was XXXX XXXX XXXX for a work related trip. I had used my card Citibank bank card attached to my Ciitbank business checking account for my XXXX XXXX XXXX XXXX XXXX XXXX XXXX XXXX. When I woke up the next morning, the account was all of a sudden severely overdrawn. I noticed that the running balance of posted transactions was way off and had gaps in it even when the transactions were already posted. I had to call customer service 4 times and finally I was then connected with tech support who acknowledged that there was a glitch and some transactiions were being double counted and I was advised to let the balances clear and it would all straighten out. I did do that but had to call back to get a bunch of the overdraft fees cleared out. However, this problem kept happening. I really did not have a chance to delve into my account every day by mid XXXX, when I was almost certain I had plenty of funds, again I was overdraft. In XXXX things snowballed out of control only because the erroneously assessed fees were then putting me into an actual overdraft state. Between XXXX and XXXX alone I was charged more than {$3100.00}. This is ridiculous. I have spent literally more than 7 hours on the phone with customer service and about 4 hours in branches. The customer service phone people first tried to tell me originally that these were not Citibank fees. Then they said they were. Then I was told that the fees would have to be reversed at the branch level. I went to one branch and was told they would look into it, then was told to go to the branch I opened the account in but the banker assigned ot me was out of town. Another nearby branch manager went to take a look but then she was going out of town so she had a business banker go on the phone with me with customer service. I literally on that phone call spent 45 min asking for an explanation of just one overdraft charge that was assessed on XX/XX/XXXX ( By this point I have noticed fees were being assessed throughout the whole year when as one can see from the balances on the statements, is just not possible ) and after being threatened that my account would be closed if I left it overdrawn ( it was about {$1500.00} that day ), I still had no answer on just one transaction. Conveniently the customer services computer system didnt go back that far for her to be able to see. I have been told twice at the branch level that the fees are accurate and there is nothing they can do until I then demonstrated not only did I have screenshots that clearly shows the running balance is not being calculated properly, but I also showed them the notices I was sent by mail stating that on XX/XX/XXXX for example the available balance at the beginning of the day was {$100.00}, but on this day in particular, I had take a client and my assistant out to a nice lunch, my assistant and I had a drink at the bar after our client left, and I filed articles of organization and paid the filing fee for a new client that day. I would not have been able to use my card had that been the available balance. The other example is that the notices say my available balance at the start of a day isXXXX  {$480.00}. At the end of the day it was XXXX  {$1500.00}. But the notice for the very next day states that my available balance for that day started at {$120.00}. But there are no transactions whatsoever that could explain how {$1700.00} all of sudden becoming available when nothing had been deposited for a few days in that account so therefore nothing was waiting to clear. Citibank is now conducting another investigation after I stated I would take this to court if need be. I feel like Citibank is caring ore about not wanting to admit fault, not wanting to credit anything, and wanting me to XXXX XXXX  This has devestated my business and has had some serious implications on me personally.