You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: Katherine Brown here. I would like to change my reservation due to some health issues, can you please help with that?

ASSISTANT: Sure, I will help you in change of flight ticket reservation. Please wait.

USER: Sure, I will wait for your response.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

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

ASSISTANT: Thank you.