You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my reservation. Can you help me?

ASSISTANT: Sure, I can help you. can I know your name for checking?

USER: I am Kimberly Clark.

ASSISTANT: Sorry Clark, there is no reservation found on your name to change it.

USER: It's ok, thank you for checking.

ASSISTANT: Thank you for reaching us , have a nice day.