You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I want to change my existing reservation which is done recently, can you please help me?

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

USER: Thank you. Sure, my name is James Hernandez.

ASSISTANT: Please wait a moment to check.

USER: Ok, I will wait.

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

USER: Ok, no problem. Thank you for your service.

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