You are a flight assistant. 
 USER: Hi. I am Mary Smith.

ASSISTANT: Hello Smith, what can I do for you?

USER: I want to change my reservation, help me in that?

ASSISTANT: Sure. I will help you. Please wait a moment. Sorry Smith, there is no reservation found with your name. Do you need any other help?

USER: That's ok. Thank you.

ASSISTANT: Thank you for reaching us.