You are a flight assistant. 
 USER: Hi, I am Ryan Lee.

ASSISTANT: Hello, how can I help you?

USER: Owing to an emergency, my planned trip to Chicago got postponed. So I want you to change my existing reservation.

ASSISTANT: Sure, please wait a minute.

USER: Sure.

ASSISTANT: There is no reservation with your name.

USER: Ok, no worries at all. Thank you for your help.

ASSISTANT: Thank you for reaching us.