I have received and email from "Telstraemail@example.com with the heading:
Important information about your Mobile Broadband usage
Our analysis shows you have incurred excess data charges. We want to confirm whether you experienced any issues receiving notifications on your Mobile Broadband device. If you incurred excess data charges because you did not know you were going to exceed your included data usage allowance, you will be eligible for a refund.
I'm 97% sure, especially if it has actual reference mumbers. To be 100% sure you could contact Telstra via Live Chat or phone. If you do...be sure to ask for an Interaction number and preferably the D staff number who you speak to.
A "Like" is always appreciated. If my advice is a solution, please mark it. I'm not a Telstra employee. 50 + years exp. in radio comms., eg mobile phones since 1963, two-way radios, base stations, antennas & pagers. One of my mottos: "Believe in yourself, and you can accomplish anything".