I was keeping everything the same (same dates/times). I just wanted the difference in the price. When I called, they told me that would give me airline credit for the difference. The credit had to be used within one year. The man that I talked to told me that I could use it to purchase anther flight at anytime in the next year or that I could use it to upgrade our current flight to "biz class" for $35./person if there were seats available the day that we fly out (we can't look into this possibility until we check in). Anyway, I would definately call.