You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation, due to some health issue. Can you please help me out?

ASSISTANT: Sure, I am here to assist you. May I know your name?

USER: My name is Lisa Smith.

ASSISTANT: Thank you. Please stay online for a while.

USER: Sure, I will wait for your response.

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

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

ASSISTANT: You are most welcome.