Activation Lock is requesting your password

Hi Everyone, I lost my phone about a month ago in Victoria, and reported it as lost on 'Find My'. two days ago i received an email stating that Activation Lock is requesting your password on (insert name) iPhone (iPhone 11). and at the same time that someone in Queensland was trying to access my apply account. I can not find out any information on what to do next. Any suggestions, ideas or actual support from Apple would be great. zmcw