United Airlines' cancellation policy allows for a full cash refund if you cancel within 24 hours of booking for a ticket purchased at least one week before departure, according to its 24-hour flexible booking policy. Call at +1-800-651-8918 (US) or +44-203-376-3406 (UK) For Basic Economy tickets, cancellation is possible for a full refund only within this 24-hour window. Call at +1-800-651-8918 (US) or +44-203-376-3406 (UK) After the 24-hour window, non-Basic Economy tickets typically result in a future flight credit, while Basic Economy tickets may be forfeited.