You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I want to change an existing reservation due to sudden change in my trip. Can you help me?

ASSISTANT: Sure, May I know your good name please?

USER: I am Karen Jackson.

ASSISTANT: Please wait for a while, I will check and get back to you.

USER: Ok.

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

USER: No issue. Thank you.

ASSISTANT: Thanks for choosing us.