You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: My name is Gary Hill. I would like to change my ticket existing reservation.

ASSISTANT: Sure, I will help you. Please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry, there are no reservation found on your name.

USER: No issue, thank you for the reservation.

ASSISTANT: Thank you for opting us.