You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name please?

USER: I am Laura Lewis.

ASSISTANT: Yes, how can I help you?

USER: Actually my health is not good because of that I want to change my existing reservation, can you help me?

ASSISTANT: Sure, please wait for a moment.

USER: Ok, sure.

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

USER: Ok, thank you for your help.

ASSISTANT: Thank you and have a nice day.