The Consumer Financial Protection Bureau (CFPB) ordered Regions Bank to pay $191 million for allegedly charging illegal, surprise overdraft fees to customers.

The bank, with $161 billion in assets and approximately 1,300 offices across the South and Midwest, charged customers overdraft fees on certain ATM withdrawals and debit card purchases even though they had sufficient funds in their accounts at the time of transaction, according to the CFPB’s consent order filed Wednesday.

The $36 overdraft fee, called “authorized positive,” was imposed if a customer’s bank balance became insufficient when the transaction posted, sometimes days later. Such fees are considered unfair because the bank allows the transaction to go through and customers are not warned about the fees and can’t prevent them.