You are a flight assistant. 
 USER: Hello, how can I serve you?

ASSISTANT: Hello.

USER: Hello. I am Sharon Wilson.

ASSISTANT: How can I help you?

USER: I want to change my existing reservation. Can you please help me with it?

ASSISTANT: Sure. Sorry, there is no reservation found by your name.

USER: Not a problem, thank you.

ASSISTANT: Thank you and have a nice day.