I just upgrade my service to NBN and the connection is terrible, the internet is very weak and it disconnected many times in a day i cant use anything properly.
Please let me know how I can contact the support inmmediately for it .
Phone Optus, or use LIVECHAT on this site (24/7) to talk to customer service. You might need them to organise a tech to look at your line.
Also run some speed tests at different times of the day to see what connections you are getting.
Sorry no one has been able to get back to you.
All contact information is available here → How to Contact Optus
Tech Support are available 24/7 on 131344 or via Live Chat.