You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be at your service?

USER: I want to change my existing reservation. could you help me with that?

ASSISTANT: Certainly, I can help you with that.

USER: Thank you.

ASSISTANT: May I know your name to check the reservation list and revert to you?

USER: Justin Turner here.

ASSISTANT: Ok, please give me a moment.

USER: Ok.

ASSISTANT: We could not find any active reservation by your name.

USER: That's ok, no problem. Thank you for helping me.

ASSISTANT: Thank you for reaching us.