Originally Posted by aaupgrade

Unless the rules are different in Ireland, or things have changed at AA, this option will not work. AA allows you to hold reservations until 23:59 CT the next day (unless the selected fare expires at midnight) but then once purchased, if the fare type is non-refundable then you cannot get a refund even if it is within 24 hours or purchase. UA on the other hand does not allow you to hold reservations, but you may get a full refund if cancelled within 24 hours of booking. Note that there are sometimes exceptions to this rule given extenuating circumstances.