You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what help are you seeking form our agency?

USER: I want to change my recent reservation, can you help me out?

ASSISTANT: Ok, may I know your name for checking with your existing reservation?

USER: I am Sandra Martin.

ASSISTANT: Give me a moment to check with your existing reservation.

USER: Ok, take your time.

ASSISTANT: Sandra Martin, I regret to inform you. There is no active reservation by your name.

USER: That's ok. Anyways, thank you.

ASSISTANT: Thank you for choosing our agency.