This app was mentioned in 3 comments, with an average of 4.33 upvotes
What /u/welcometo1984 said is correct.
Another thing that you might find useful in future if you have an Android device or an iPhone is an app which has a digital Health Care Card. If you forget your physical card but you have your device with you, you can use the app to show your concession card and avoid getting another fine. The app is accepted as proof of eligibility for concession fares on all PTV services.
the best advice i can give is sign up for my gov then centerlink and do the forms then download this app for documents
https://play.google.com/store/apps/details?id=au.gov.dhs.centrelinkexpressplus&hl=en_AU