icelandair cancellation policy

hi! i'm looking for any tips on the below: (sorry for the long text)

so i booked an icelandair ticket to norway in august and the trip was scheduled for october. it was the economy light fare. i ended up receiving a medical diagnosis two days before the flight and my doctor advised me not to go on the trip so more tests could be done. i tried getting a refund on the flight but icelandair would only give me a partial refund of the unused fees and taxes. i tried multiple times but they all said that was all they could do because it was the economy light fare and i didn't purchase a cancellation policy ahead of time. (this isn't my first time booking with icelandair and i never saw that as an option). my first call to icelandair was the day after the flight took off. when i called again a little while later, i was told that i was marked as a no-show because i didn't call them ahead of the flight. i honestly did not even have time to think about it because of all the tests i had during that time.

i tried submitting a claim through my bank but i just got the letter back in the mail. it said they are unable to honor my claim because "a cancellation was not made or attempted prior to the expected date(s) of service."

i just find it hard to believe that icelandair will not do anything else. i understand purchasing the cancellation policy (now that i know that's an option) but i had every intention on going on this flight. i'm not trying to get special treatment for the medical diagnosis but i feel like that's an understandable reason for missing a flight? common sense to call ahead of the flight takeoff. i would just hate to be out of this money so i wanted to see if anyone had tips on something else i could try.

thank you!