Complete disrespect to customers/ Horrendous service

Hi Jetstar,
You lost me as a customer. Thanks to the poor service and condescending manner of your service desk staff at Sydney airport. I missed my flight by 3 minutes due to unfortunate circumstances. They closed the gate despite I told them on the phone at 8.02pm that I had passed security screen and would be there in a few minutes. The departure time was 8.15pm and I was there at the gate at 8.06pm only to see the closed gate and no staff around.
The girl at your service desk offered me to pay $50 change fee or full price for a new ticket if I argue with her. I calmly asked her if she can waive the fee as I were your regular customer. Next thing I know, she refused to help me to rebook and told me my only option was to pay full price for a new fare, my current fare was forfeited in full due to no show, despite i was there in their face. I lodged a complaint on your site and received a standard reply. I sent a followup response and haven't heard back since. I should have paid for the ticket by credit card and raised a charge back, lesson learnt.
Now my only option is to go to the airline complaint site and ACCC, let's see how it goes but I don't hold high hope on this.

TLDR: fare forfeited despite I was only a few mins away from the gate and had cleared security (they knew this when called me up). Staff at (non)service desk forced me to pay full fare for replacement flight as a punishment as they thought i was being difficult and arguing with them.
Don't flight with Jetstar, if you absolutely have to, remember to pay by credit card as you can request a chargeback.

Domestic
Australia-Sydney
Australia-Sydney