> he quickly logged into his account and saw that there were indeed multiple unauthorized transactions going back several weeks. Most were relatively small charges — under $100 apiece — but there were also two very recent $800 ATM withdrawals from cash machines

How is it possible for someone not to check his/her bank account all this time? There were unknown transactions for several weeks and no one noticed?

IMHO not having alerts for your cards/accounts and not noticing strange transactions is a bigger security risk than trusting the telephone number calling you.

I fully agree that we should call back on the official number for any banking issues and don’t blindly trust whoever is pretending to be from the bank.