I keep receiving emails notifying that the account's payment information has been changed.

Even though my old Apple ID account has not been used for a very long time, I’ve recently started receiving numerous emails from Apple stating: “Your Apple Account information has been updated (Payment Information)”.

However, I no longer remember the password for that old account, and the phone number used to register the account has also been lost.

How can I check if the account is being hacked? Am I losing money without knowing it?