You are a flight assistant. 
 USER: Hello. My name is Thomas Williams.

ASSISTANT: Hello, how may I guide you?

USER: Actually, I booked a ticket to NYC for a music concert, but due to a medical emergency, I want to change my reservation.

ASSISTANT: Sure, please hold on for a moment.

USER: Sure, take your time.

ASSISTANT: Apologies Thomas, there is no such existing reserved ticket on your name.

USER: That's ok. Thank you for your time.

ASSISTANT: You are welcome Thomas.