I deposited money one day and usually they say that yes, it will be available the next day. However later its website said that the funds were there, not all, but it was there. I took out some money from an ATM. I got a letter saying I over drafted. Is it right that there website lied about how much was in my account? I have a screenshot of it from that day as well. Should I go complain?

Yes complain and TAKE the screen shot with you

When you say you deposited "money," do you mean CASH? If yes, I'd complain.

If you deposited a check, it is unrealistic to think the money will be available the next day. You should NEVER, EVER count on money from a check being available until the check actually clears.

A check is just an I.O.U. Are you going to blame the bank, too, if the check bounces?

If the bank has a habit of allowing you to access the funds from deposited checks the next day, that is a COURTESY and you should be saying "thank you" rather than complaining because one time it didn't happen.

If you need funds from a check right away, then you CASH the check and then deposit the cash.

They didn't lie! Your deposit was in the form of checks that the bank puts a hold on until they clear the issuing bank.

have a sit down with your banker