Newcastle staff cancel written boarding times to force passenger to pay double and await next flight

I arrived at the Newcastle boarding gate with my boarding pass and was outside the 10 minutes cutoff tie zone that would otherwise prevent me from boarding. i had checked before departing brisbane with jetstar staff what the window was up to 10 minutes before departure time fo rthe newcastle airport flight so that I would be prevented from boarding the plane if fog and rian slowed my arrival time. When I reached the terminal gate to the tarmac it was 12 minutes before baording...I looked at the boarding ladder up agianst the plane I looked at the time on the ticket for departure and showed my boarding pass issued by internet the day before. The staff said you cant board because we have given the passenger list to the pilot and he has signed off on it so you must go on the next flight . They refused to accept my ticket despite the fact I was just 20 m from the boarding ladder outside the 10 minute cutoff they all agreed was Jetstar policy. They then led me back to the counter to swap my ticket to the next flight but the console operator refused to allow me on the next flight, claiming it was full. Only after I had to demand from other assistant staff to see the manager would the console officer admit there were spare seats and thern he billed me for the swap a massive exra 80 dollars.
I t is an outrage that a member of the staff can just cancel boarding rights within the allowed boarding times because they dispatched the paperwork early it is wrong they can deny a swap ticket for the next flight by using a lie they have no seats and defy my ticket rights until threatened with management intervention for their behaviour. They should be stood down for the stuff up they made o f my day, my employment and my right to have what Brisbane staff told me before I left for Newcastle would be my rightful boarding window of time to climb aboard a plane that was only half full.