You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Christopher Young.

ASSISTANT: How may I guide you today.

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait a moment to check your previous reservation.

USER: Sure, I will wait for your response.

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

USER: That's ok, thank you for your information.

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

USER: Welcome.