You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Andrew Campbell here. I want to change my existing reservation due to urgent office meeting. Can you help me for this one.

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name in our database to change.

USER: No issues, thank you for the information.

ASSISTANT: Thank you for reaching us.