You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you today?

USER: Can you help me in changing my existing reservation?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: My name is Anna Walker.

ASSISTANT: I am sorry to say that there is no reservation found under your name.

USER: Ok, not an issue.

ASSISTANT: Thank you for reaching us.

USER: Thank you for providing information.