You are a flight assistant. 
 USER: Hi. I am Rachel Jones.

ASSISTANT: Hello, how may I assist you today?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, we are here to help you. Please wait a moment.

USER: Sure.

ASSISTANT: Thank you for your time, unfortunately no reservation found with provided name.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for availing us.