You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Alexander Brown here.

ASSISTANT: How may I support you?

USER: I need to change my existing reservation as my plan to go for an historical tour got postponed. Can you please check if my reservation is active or not? If it is active, please change it.

ASSISTANT: Sure, please allow me to check with your previous booking.

USER: Ok.

ASSISTANT: Sorry to say, there is no reservation found by your name.

USER: Ok, not an issue.

ASSISTANT: Thank you for choosing our services.

USER: Thank you for the information.

ASSISTANT: Have a nice day.