You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I best serve you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, please share me your good name.

USER: I am Gary Lewis.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: Ok, no problem.

ASSISTANT: Thank you for communicating with us.

USER: Thank you for your information.