Hey @Shiv_98, I'm assuming this is an ADSL connection?
Remote testing for ADSL is limited, so if we can't identify a fault on our end, a technician is required for further investigation. Optus are responsible for supplying the internet to your property, so the $150 fee only applies if something on your end is causing the issue like a third party modem, incorrect set up etc.
As long as you're using the standard set up as instructed when connecting, all technician costs will be covered by Optus. Anything else would require a private technician.