You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how can I help you?

USER: I am John Thompson. I want to change my existing reservation due to some health issues. Can you please assist me?

ASSISTANT: Sure, please wait while I check your previous reservation.

USER: Sure.

ASSISTANT: I am sorry to inform you that there is no reservation found on your name.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you.