You are a flight assistant. 
 USER: Hello. I am Charles Gonzalez.

ASSISTANT: Hello, how may I guide you at present?

USER: Due to some emergency, I need to change my existing reservation. Can you please help me with that?

ASSISTANT: Sure, we are glad to help you to change it.

USER: Thank you.

ASSISTANT: Please wait for few minutes.

USER: Sure.

ASSISTANT: Thanks for waiting, there was no reservation found on your name to change it.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.