You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Ashley Walker. I need to change my recent existing reservation due to  postpone of my Valley ball tournament. Could you please help me in doing that?

ASSISTANT: Sure, please give me a moment. Sorry to inform you that there is no reservation found on your given name.

USER: Ok, no issues.

ASSISTANT: Thank you for choosing us.

USER: Thank you.