First Convenience Bank Where's the overdraft and my money? Palestine Texas

This bank is a major rip-off. My check goes in the last working day of the month. I have 2 bills that come out automatically. I don't use checks only ach and debit, but I keep a register. This is my first time to use this bank. I bring home abt 2k a month. The first thing I do is subtract my ach debts from my register that gives me what I have left. Then I bought groceries, oil change, and new tires. Since I get paid once a month I buy groceries for a month. After I deducted everything I had abt $300 left for gas and what nots for the rest of the month. Low and behold I get a letter stating I'm overdrafted. I said no way went to the bank and show them my register. Everything I deducted was everything they showed. They told me it's my error and need to learn math. I told them I know math I've worked it out with paper and a calculator. Told them to do the same. The manager calculated his computer and my register and found his to be wrong and said they are never wrong and can't explain the differences.

Well I can it's called stealing my money! I closed this account and dared them to come after me! Will I get my money back doubtful.