You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am Sandra Taylor. I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, please wait. I will check the reservation on your name and revert to you.

USER: Thank you for considering my request. Sure, I will wait for your response.

ASSISTANT: Sorry, we couldn't find a reservation on your name to change.

USER: That's ok, not a problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.