You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Lisa Parker. Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait a while.

USER: Sure, I will wait for your reply.

ASSISTANT: Sorry to say, there is no reservation on your name in our database.

USER: That's fine. Thank you for your information.

ASSISTANT: Thank you for opting us. Have a nice day.