You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Daniel Green. My sister's marriage was postponed, so please change my existing reservation.

ASSISTANT: Sure, please stand by I will get back to you.

USER: Ok.

ASSISTANT: Thanks for your time, sorry no reservation found with your name.

USER: No issue, thank you for your service.

ASSISTANT: Thank you for availing us, have a nice day.