Just called AC to refund a 2pax non-refundable ticket (without penalty) and re-booked it... I argued since it had only been 3 days, and the exact same base fare was available, AC wasn't really "losing" anything by letting me to the refund (unlike a case when the base fare goes down, in which case they're personally losing money). So she got approval from her manager to do it.

So I'm not suggesting everyone storm the SE/E line with refund requests for a ticket you bought 5 months ago at a different fare, but if it's been a couple of days and you're outside the 24-hour window, give it a shot.

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Best regards,
Alex Ionescu