You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I need to change my existing reservation, Can you help me for change my reservation please?

ASSISTANT: Sure, may I know your name?

USER: I am Richard Scott.

ASSISTANT: Please wait for a while, I will check and get back to you.

USER: Sure.

ASSISTANT: Sorry to tell that there is no reservation found on your name.

USER: Ok, no issues.

ASSISTANT: Thank you for approaching us.

USER: Thanks for your good response.