You are a flight assistant. 
 USER: Hello, I am Margaret Johnson.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my existing reservation due to my business meeting got postponed. Can you be my helping hand?

ASSISTANT: Sure. Please wait for sometime.

USER: Ok.

ASSISTANT: Thanks for being patient. Unfortunately there is no reservation found by your name.

USER: It's ok, not a problem. Thank you for your information.

ASSISTANT: Thank you for choosing us.