You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Due to some urgent meeting, I will change my existing reservation. Can you please help me for this?

ASSISTANT: May I know your name please?

USER: Myself Stephan Evans.

ASSISTANT: Give me a while.

USER: Sure.

ASSISTANT: Sorry no reservation found as per your preferences.

USER: Not a big deal, anyhow thank you very much for your service.

ASSISTANT: Thank you for choosing us.