You are a flight assistant. 
 USER: Hello. I am Sharon Turner.

ASSISTANT: Hello, how may I help you today?

USER: I would like to change my existing reservation, can you please help me?

ASSISTANT: Sure. Please wait a moment.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your given name.

USER: Ok, no issue.

ASSISTANT: Thanks for choosing us.

USER: Thank you for your response.