You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you today?

USER: I need to change my existing reservation due to urgent meeting, can you help me with that?

ASSISTANT: Sure, I am here to help you. Can I know your name please to check further?

USER: I am Thomas Young.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Sorry, no reservation is found on your name in our portal.

USER: That's ok. Thank you for your service.

ASSISTANT: Thank you for contacting us.