Information about why you might get the message "An error has occurred." when you try to add a payment method
How to remove or change the phone number on your Battle.net account
How to move a Hearthstone account off a Battle.net account
How to correct an email mistake when creating or updating your Battle.net account
A BattleTag can only be updated for free once
It is not possible to move a Call of Duty account to another Battle.net account
Information on where to update your Activsion Account Email