Ahhh I went through this last week. Took me 4 days to work it out.
Here's a cut n paste of the solution i posted up, hope it helps
To everyone trying in vain to contact Optus tech support, I have found the answer thanks to a fellow Optus user I found in this forum.
Call 133 344 jump through all the menus as required until it asks you to sign up for SMS reporting....
now here's the secret, at this point, don't do anything, press any button, anything!! Just wait, it'll ask you a further 2-3 times to sign up for SMS reporting, then hang on the line and BINGO, someone will answer your call.
I just got off the phone with them, they were very pleasant and helpful and I got my internet back working.
Needless to say, to get to this point took 4 frustrating days and Optus need to take a massive look on how they treat their customers.
I hope this helps some of you