On the old CO, there was a written (as in online) 2 hour policy. I used it to my advantage once. Had a CO ticket IAH-NYC. Realize I miscalculated my EXP requal and then just purchased a new IAH-DFW-LGA ticket. There was a storm in NYC and everything was late. Filed for a refund of my CO ticket due to a 2h10m delay and it was promptly granted.