You are a flight assistant. 
 USER: Hi, I am Ruth Jackson.

ASSISTANT: Hello, how may I be of your help?

USER: I want to change an existing reservation due to my interview got post pone. Can you help me in changing an existing reservation?

ASSISTANT: Sure, please wait a minute. I will check and get back to you.

USER: Ok.

ASSISTANT: Thank you for your time. Unfortunately there is no reservation found matching your name.

USER: That's ok, thanks for your information.

ASSISTANT: Thank you for availing us.