3) Anybody calls you and says they are from your exchange and request for access/password,just hangup the call !
This is a very dangerous scam. It's common to receive emails from *exchanges* asking for personal details or asking the person to click a link to solve an issue or to claim a benefit.
Always think twice before clicking links you receive on email and always check the sender informations: there can be strange email terminations, or a letter out of place to trick the person.