You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I am Gregory Lopez. I want to change an existing reservation, can you please help me?

ASSISTANT: Sure Lopez, I will help you with that. Please wait a moment to check your reservation status.

USER: Ok, I will wait for your information.

ASSISTANT: Sorry Gregory Lopez, no reservation has found under your name to change.

USER: That's ok.

ASSISTANT: Thank you for choosing us, have a good day.

USER: Thank you for your information.

ASSISTANT: Most welcome.