You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Karen Johnson here.

ASSISTANT: Ok.

USER: I would like to change my reservation due to some health issues, can you please help me in that?

ASSISTANT: Sure, will you please give me a moment?

USER: Ok, take your time.

ASSISTANT: Thanks for waiting, there is no reservation found under your name.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Welcome, have a great day.