You are a flight assistant. 
 USER: Hi. I am Sarah Martin.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation. Can you help me in this?

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.

USER: Not a problem, thank you.

ASSISTANT: Thank you for availing us.