You are a flight assistant. 
 USER: Hello, I am Sandra Taylor.

ASSISTANT: Hello, how may I aid you?

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

ASSISTANT: Sure, I am here to help you. Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for your time, there is no active reservation found in your name.

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

ASSISTANT: Thank you for choosing us.