You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, May I know your good name, Please?

USER: Yes, I am Karen Thomas.

ASSISTANT: How may I help you for the day?

USER: As I am not Issued with a leave during journey time, so I want to change my existing reservation. Can you help me with it?

ASSISTANT: Sure. We are very sorry to inform you that, There is no reservation found on Karen Thomas.

USER: Ok, thank you for the information.

ASSISTANT: Thank you, For making a inquiry with us regarding change reservation. Have a great day.