You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you for this moment?

USER: I want to change my reservation, can you help me?

ASSISTANT: Sure, I will help you with this. May I know your name please for further process?

USER: Myself Andrew Clark.

ASSISTANT: Ok, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry Clark, there is no reservation found as per your name to change your reservation in your database.

USER: No problem, thanks for checking.

ASSISTANT: You are welcome.