You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I amend you?

USER: I need to change my existing reservation due to postpone of my document verification in my office. Could you please help me with changing my reservation?

ASSISTANT: Sure, may I know your name to check in the reservation list?

USER: My name is Andrew Brown.

ASSISTANT: Sorry, there is no active reservation found in your name.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for approaching us, hope to serve you again.