You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you?

USER: My name is Andrew Harris. My friend marriage was postponed, so please change my existing reservation.

ASSISTANT: Sure, I will help you in this. Please wait a moment.

USER: Sure.

ASSISTANT: Thank you for your time. We are sorry to inform you that, there is no reservation found with your name.

USER: No issue, thank you for your service.

ASSISTANT: Thank you for reaching us. Hope to serve you again.