Back in November I had to cancel a flight on short notice due to illness (MD said I shouldn't fly & offered to write a note), so apparently I have a credit "somewhere". However, I'd already booked four itineraries, my "last" flight of 2012 & three itineraries in 2013. So I asked if the $$$ could be applied to any of these, but the agent sighed & said it would be a lot of trouble, so just apply it to a future flight in 2013. IIRC, it would be a rebooking on the old PNR. So what to do about the now-stale(?) doc's note; somehow deposit it for credit with UA, or hold on to it & try to apply it to that future booking? Also, something was said that even with a medical excuse there'd be a $50 fee. Bottom line, I *think* this boils down to a net $100, assuming the normal $150 rebooking charge w/o a medical reason. Anyone have a similar experience?