Ok, your statement was returned to USB which means one of two things.
1. You never changed your address with the bank (or at least made sure it was right)
or
2. It's a problem with the post office
Either way, this doesn't strike me as bank error. Besides, how could they mail you an overdraft notice if your statement is being returned? And please don't give me that "well, they need to call me on the phone" crap. If USB tried to call every overdrafter every day, they'd never get anything else done. Also, it sounds like you didn't check your balance for, by my calculations, roughly fifty days. ($8 daily negative balance fee times fifty days equals $400.) That tells me you're not exactly vigilant with your finances anyway.
And by the way, the fee was disclosed to you when you opened the account. You actually signed a document stating that you have read, understand, and agree to all terms of the account, including the returned statement fee.