I previously responded on one of your older posts about this issue.
Live chat is avalible via two different methods:
If you are having trouble with the app live chat, may I suggest that you uninstall and reinstall the mobile application.
If your issue is with the support chat on the website. Please take a second to clear your browsers cache/cookies for Optus.com.au.
Do not close the chat window, or let your computer/device to go to sleep/lock.
If this does not resolve your issues, you can call Optus on 133 937.
Please reply to this thread for future corrispondence in regards to this issue instead of opening a new one.