You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Katherine Jones here.

ASSISTANT: How can I help you?

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

ASSISTANT: Just a moment please.

USER: Ok, take your time.

ASSISTANT: I am sorry no reservation found on your name.

USER: That's ok, no problem. Anyway thank you for checking out.

ASSISTANT: Thank you for choosing us.