Re: 402 customers?
"...Me, I keep my personal account in a completely different bank for multiple reasons including that they can't rob 'Peter' to pay 'Paul'..."
This is called "setting-off". I must admit, I'd thought they'd been stopped from doing this, but apparently not: https://www.moneysavingexpert.com/banking/setting-off
It allows banks to take money from savings or current accounts to pay debts such as credit card or loan arrears