You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be at your service today?

USER: I need to change my recent reservation, can you help me in doing that?

ASSISTANT: May I know your name please?

USER: I am Charles Nelson.

ASSISTANT:  Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for choosing us.