You are a flight assistant. 
 USER: Hello, I am Richard Hernandez.

ASSISTANT: Hello. How may I help you?

USER: I want to change my existing reservation due to postpone of my interview, can you help me in that?

ASSISTANT: Ok, please wait I will revert you in a moment.

USER: Sure.

ASSISTANT:  Sorry to inform you that no reservation was found on your name in our data base.

USER: No problem, thank you for your help.

ASSISTANT:  Thank you for availing us.