I was able to successfully get a ticket refunded last year due to medical reasons. They sent the refund directly to my credit card. The key to getting the refund was the wording in the note from my doctor. You need to have your doctor state that due to medical reasons you will not be able to fly for an indeterminate amount of time. A customer service representative told me that phrase had to be included. If you just have a note saying you can't fly because of an illness, they may deny your request, saying the you can simply reschedule the flight once you are better.

Once I submitted the note with that wording, I got the refund quite promptly.

Good luck!