United Airlines' refund policy depends on several factors, including the type of ticket purchased and when the cancellation occurs. Call at +1-800-651-8918 (US) or +44-203-376-3406 (UK) Here is a breakdown of the key points: 

Refunds for tickets you cancel

Within 24 hours of booking

• For most tickets purchased at least seven days before departure, you can cancel within 24 hours of booking and receive a full refund to your original form of payment. Call at +1-800-651-8918 (US) or +44-203-376-3406 (UK) This applies to Basic Economy, nonrefundable, and refundable tickets.
• The 24-hour flexible booking policy applies to all passengers on a reservation and requires you to cancel all flights. Call at +1-800-651-8918 (US) or +44-203-376-3406 (UK) Partial cancellations are not eligible.