Illegally charged for return air flight

I was on a flight to Phuket from Sydney routed through Melbourne. Planes were changed in Melbourne but not the Flight number, so I was legally on the same flight. There was a slight delay in Sydney take off due to weather and when we changed planes in Melbourne, staff were in a hurry. On checking in for the new plane, I was told I had to have a return air ticket with Jetstar, not one way, which I had. I told the staff a) I had a Visa to visit Thailand (not visa on arrival), this means one doesn't need a ticket out when you arrive. b) That I already had tickets booked out of Thailand on another airline.
The staff insisted that I buy a return Air ticket, not to Sydney but to Melbourne, despite the fact I don't live there.
I told them they had no jurisdiction to decide a matter such as that. They said they did. (They DONT' EVER).
(THE RULE IS) They can only advise a customer that if foreign Immigration do not allow you entry (for any reason), they Jetstar or any airline, are not obliged to fly you out again. You have to make your own arrangements.
After much disagreement they advised me they would not allow me (back) on my booked and paid for flight if I did not purchase a return air ticket on the spot. I bought a return air ticket to Melbourne under extreme duress.
They were now threatening that because this had all taken so long the plane, my flight, may take off without me.
When I returned three months later via another airline, I applied for a refund.
The refund took six months 6 phone calls and three threatening letters to get, MINUS $35 for administration costs!!!
That's $35 they owe me in cash and at least $3,000 in stress and inconvenience.
As an adjunct to this story. While I was in Melbourne filling out my departure card at customs, despite the hall being totally empty, despite me now being in an extreme hurry, the customs staff officer refused to let me fill it out on the counter in front of her and demanded that I go to the back of the hall and use the desk there, where I was supposed to!!! I am really at my wits end as to how bureaucrats and people with a tiny bit of power, and airport officials and staff in this country, are uncooperative in their spirits to the point of blatant obstructionism and pointless power plays. I regret not following this up legally. It would have taught them a lesson.
I now fly exclusively foreign airlines. The things foreign airlines have allowed me to do and achieved for me in the meantime would fill a book. Wake up Australia.