I've actually followed some advice I saw on other FT posts and initiated a credit card dispute for the taxes and fees amount.

Especially as Expedia started off by assuring me that the ticket was entirely non-refundable and I wouldn't get a single paisa back. I only initated the refund after calling Finnair, confirming from them that I'd get my taxes and fees back, and that they'd refund the amount within 15 days of Expedia sending them a refund request ..

Now its 2 months since the date of cancelation and they haven't even sent the request to Finnair.