Refund/ compenastion for cancelled Air China international flight

I made the mistake of booking a return flight (799 UK pounds = 1550 Australian dollars) from Copenhagen to Melbourne with Air China.

The outbound flight in January was okay, but in March they made a schedule change to my return flight in July - one which did not suit my schedule.

I tried to rebook the flight to go back one week earlier instead. This took ten expensive and time consuming phone calls, and five weeks to succeed - even though they were the ones originally changing their schedule.

Three weeks later I received an email from them apologising that they had to cancel the second leg of the return trip (Flight 1 was Melbourne - Beijing, second leg Beijing - Stockholm, and third leg Stockholm - Copenhagen).

Since I needed to be in Copenhagen on this specific day and I had had enough of their schedule changes and incompetence, I called them and said I wanted to cancel the return flight and get a refund. I was told by two people I would get a full refund, another two said it needed to be calculated, and a third person didn't know. However, everyone I spoke to agreed it would take 7-8 weeks to process before I had the money back in my account.

Everyone failed to mention that in order for the refund to be processed, I needed to be sent a refund form, fill that out and send it back. I only found that out two months later when I called to ask why I hadn't received my refund yet.

The form was then sent to me with the refund amount of US$256.80 (about 345 Australian dollars).

I called back today and was told that the amount was correct because I had already used the outbound flight and this amount is what the return trip was worth. I then said that the very same trip, except the Stockholm - Copenhagen leg (because they don't fly to Copenhagen any more) was $1136.16 on the same date but with a one day lay over in Beijing since the other flight had been cancelled. This was from their own website - which was the one I had originally booked with.

So for a $1550 dollar return trip they only want to give me $345 back, even though the same trip costs $1136 on their website.

My question is: are they allowed to do this? Can I complain?

Trying to email or ask to talk to a supervisor hasn't worked for me, as no one is replying to my emails. Their free phone number connects to somewhere where it's night time and no managers are present, and their other phone number is $2 a minute (last time I called I was on hold for 20 minutes).

UPDATE Hi and thanks for all the replies, I called Air China and again got to talk to someone who knew nothing about and all I got was an email address to write to and in detail explain what had happened, which I did in a nice and factual way. They replied within a few hours saying that after examining my case they had found that my ticket was not purchased through their website so they couldn't offer a refund at all, and telling me to instead contact my local travel agent. I replied immediately saying that my ticket was definitely purchased through their website, I forwarded them the confirmation email and a screen shot of my bank statement which clearly said air China. They didn't reply to that for five days so I emailed them again, and a week later still haven't heard anything back. My flight is suppose to depart in two weeks and I am no closer to getting a refund, in fact they have withdrawn the offer of the $256.80 which leaves me in a really bad situation since I've had to spend $1500 dollars to buy a new ticket with Thai Airways. Surely this cannot be legal what they're doing, completely denying any responsibility even though they were the ones canceling the flight, and now not wanting to reimburse me at all?? Who can I turn to to make a complaint which will lead to getting my money back? Thanks for all your help.

Sincerely Annicka