they rang, I picked up phone ans said "hello". They hung up - nseems suspicious

They called me from “commonwealth bank” asking me to pay money

Person called up my Aunt, saying they were from Commonwealth Bank. Wanted her to "check" details. She got a notification that an attempt had been made on her Commonwealth Bank account to withdraw money. She is stressed to the Max, and changing banks asap!! Scary thing is they knew her bank balance.
Call says origin was Melbourne VIC 3429. The number is associated with Symbio Networks Pty Ltd