[sof]

Hi,

Legally you should not have to pay extra for oxygen. As you booked the tickets in Australia, (I am assuming), it comes under Australian Law.
As you were told (before you booked your ticket) that oxygen would be free, that is part of your contract. It is clear you would never

Regardless of what you have decided to do, you should:
a.) be able to get the full price back (damages) (with no cancelation fee) due to fraud/deceit or due to their breach of your contract. or
b.) be able to get the oxygen for free, as you were told.

I would go see a lawyer or the ombudsman if I were you (if you are tight with money - the ombudsman would be the best way to go).

It is really their fault as it is obvious you would only have booked your ticket if the oxygen was there and free. You have tried to find out how to get it but have been constantly denied by their end due to bad customer service.

Hope I could help, if you need precedent/authority for what I have said I will look it up.

Good luck!