You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am Mary Walker. I want to change my flight reservation as my trip got postponed, can you please help me?

ASSISTANT: Sure, please wait a second I will check the update.

USER: Sure. I will wait.

ASSISTANT: Sorry to inform you, there is no reservation found on your name to change the reservation.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for choosing us.