You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

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

ASSISTANT: Please wait for a moment.

USER: Sure.

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

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

ASSISTANT: Thank you for reaching us.