G'day all - thanks for all the replies. I've asked them for different email addresses but all they said to me was "sorry, this is all our email address" (sic)

I've then sent emails again to the [email protected] and [email protected]
addresses and 12 hours later I managed to receive a reply. I'm writing these email addresses here for future reference, in case some hapless soul has the misfortune of having to deal with CS Air over email again.

Btw, I've received "delivery failed" notices to the [email protected] address:
"Delivery to the following recipient has been delayed:
[email protected]
Technical details of temporary failure:
The recipient server did not accept our requests to connect.
[(10) smtp1.cs-air.com. [58.248.41.222]:25: Connection timed out]"

I was hesitant to seek the refund route as I had already known the issues with refunds posted here - and a few weeks ago I had to change the number of the credit card I used to book this flight because of a fraud issue, which would make the refund probably a horrible ordeal.

Thanks again to everyone for their replies.