You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Myself Lisa Mitchell. I want to change my existing reservation due to some health issues, can you help me?

ASSISTANT: Sure, give me a minute.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, there is no reservation found under your name.

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

ASSISTANT: Thank you for choosing us.