Welcome to the community!
I apologise for such inconvenience, I was able to locate your account using your community details. I've seen that you have been in contact with one of our Provisioning Case Manager and advised about the new schedule, Thursday, 20 December 2018, 8:00 AM - 12:00 PM.
I will chase this up with our Provisioning Team request a feedback for any update on your NBN Service Installation. Let me know should you require further assistance.