You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I want to change my existing reservation. Can you help me for that one?

ASSISTANT: Sure, I will help you with that. Can I know your name to check your previous reservation?

USER: Sure, Kevin Allen here.

ASSISTANT: Please be on hold to check.

USER: Sure.

ASSISTANT: We regret to inform you that, there is no reservation found on your name in our reservation list.

USER: No issues, thank you for the information.

ASSISTANT: Thank you for approaching us, have a great day.