Welcome to TPG Community!
We were able to locate your account using your community details and reviewed the account.
The Free 3 Months of TPG Mobile service should work without any credit as it comes with unlimited national and text. If the service is not working, our Mobile tech team will need to look into the account. However, it seems that you've already added a credit on the account and we can see the you were able to use the service now.
The credit will be used in case you'll be using the service outside the included value.
In case you experienced any issues with your service, please let us know or contact our Mobile team on 13 14 23 for real time support.