You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

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

ASSISTANT: Sure, please wait a moment.

USER: Sure, I will wait for your reply.

ASSISTANT: Sorry Anna Robinson, there is no reservation on your name.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you.