I asked them they want money to change the title that to 220 AUD.
My agent mistakenly added Ms title instead Mr on the booking.
Although I feel like the fee is high, looking at flightnetwork which is an online booking site, you have to enter your personal details with the title being mandatory. Seems unlikely that the website would mistakenly book you under the wrong title.
This is where booking directly with Qantas would have worked in your favour. If you call up with any mistakes within the day, they don't charge a change fee. https://www.qantas.com/au/en/manage-booking/same-day-no-mistake.html