Thank you for your help Basil.
Previously in my old Galaxy Note 4 I could install the TPG App then checked my mobile data usage. It's handy as I can check my data usage anytime without login to My Account to check.
I just changed my phone to Galaxy Note 10+ and can't get that option in TPG App. Do you know why?
We've updated the TPG Application, which currently support ADSL2+ Home phone, NBN and FTTB bundled service.
The new TPG application will not be able to provide details of our TPG Mobile SIM service (usage, etc.). Our Developers are currently working on the updates to support all of the services that we offer.
As of the moment, you may check the usage via TPG My Account.