You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I render you at this moment?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Sure, may I know your good name please?

USER: My name is Lisa Carter.

ASSISTANT: OK, please wait for few minutes.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name in our records.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for reaching us.