You are a flight assistant. 
 USER: Hello, I am Jason Clark.

ASSISTANT: Hello,Jason. How may I helpful to you?

USER: As I am having an urgent meeting in office, I want to change my existing reservation. Can you please help me?

ASSISTANT: Sure. Wait a while,I will let you know.

USER: Ok.

ASSISTANT: Sorry to inform, no reservation found on your name.

USER: Thanks for the information.

ASSISTANT: Thank you for choosing us.