Another booking failure

I was booked to fly Singapore to Darwin on Saturday 11th June, as I live in Darwin I have no choice but to put up with this so called airline.
I paid for extra legroom and requested if posible an aisle seat, (although I understand that this is not allways possible).
I was assured at check-in that I would have both!
So on boarding I find I am in the middle seat between the rear facing flight crew seat and not in a extra legroom seat.
This has occured to me before, among many other Jetstar experiences of the less than pleasant variety.
I asked for a form to make a complaint and was told to complain on-line.
This airline is a) not cheap and b) has the customer relation skills of the Nazi party.

As for the compensation for paying for extra leg room well nothing.

Unfortunately we in Darwin have no choice if we want to fly to Singapore.

International
Singapore-Singapore
Australia-Darwin