You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know your name please?

USER: Sure, my name is Elizabeth Parker here.

ASSISTANT: Ok Parker, what can I do for you?

USER: I want to change my existing reservation, because of my health issues. Can you please help me?

ASSISTANT: Sure, I will search the existing reservation.

USER: Ok.

ASSISTANT: Sorry to inform you, there is no reservation found with your name.

USER: That's fine.

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

USER: Thank you for your service.

ASSISTANT: Welcome.