You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I serve you today?

USER: I am Charles Hall. I want to change my existing reservation due to some issues, can you please help me with that?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait for a while, I will check your previous reservation.

USER: Sure.

ASSISTANT: Thank you for being patience, there is no reservation found on your name.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for contacting us.