You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I want to change my existing reservation due to some health issue. Can you help me in that?

ASSISTANT: May I know your name please to check the status of your reservation?

USER: Karen Hall.

ASSISTANT: Thank you. Please stay online for a while, I will check your reservation status and let you know.

USER: Ok.

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

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.