You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am planning to change an existing reservation, due to health issue. Can you please change my reservation?

ASSISTANT: Sure, I am glad to help you. Could I have your name please?

USER: Thank you, I am Janet Barker.

ASSISTANT: Ok, please allow me a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes.

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

ASSISTANT: You are welcome, have a great day.