You are a flight assistant. 
 USER: Hello. I am Charles Lewis.

ASSISTANT: Hello, how can I be your helping hand?

USER: I need to change my recent reservation due to postpone of my convocation day. Could you please help me in doing that?

ASSISTANT: Sure, please wait for a while. Sorry, we did not found any reservation on your name.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for availing us.