You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Kevin Martinez here. I want to change my existing reservation. Could you help me with that?

ASSISTANT: Ok, please wait I will revert you.

USER: Ok.

ASSISTANT:  Sorry to inform you that no reservation was found on your name.

USER: That's ok, no problem. Thank you for helping me.

ASSISTANT:  Thank you for availing us.