I called back the number (02) 9999 3283 and reached vm that said I reached Commonwealth Bank

I called CBA for a friend who is currently outside of Australia. The CBA representative gave me this number as a toll-free international number - Legitimate - however, never give your information out over the phone, always call back on a number from their official website.

This actually is the CBA's non-13 number

Caller claimed to be from Commonwealth Bank and wanted me to get the person who they called to ring them .

Scam caller, claiming to be Microsoft. Claims that your computer has an infection and needs to buy a firewall from them.