Welcome to the Community!
Our server counts the data usage of our customers accurately.
We've managed to locate your account using your community details and reviewed your data usage, but did not detect any issue.
Your daily usage is the same as when you were with our TPG ADSL2+ service, it's just the data that is being counted when you were with our ADSL is just the Download as the Upload data is not included. This may be the issue, why your service wasn't throttled or you did not receive any warning that you've exceeded your data limit.
On our NBN service, we count both Download and Upload data which is why it feels like it is much faster to consume.
We've sent an Email with your data usage report for your reference.