You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: I've planned a tour to Dallas but my leaves hasn't got approved. I would like to change my Change my existing reservation. Will you help with this?

ASSISTANT: Sure, may I know your name?

USER: My previous reservation has done with my name Lisa Evans.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found.

USER: Ok, not an issue. May be something went wrong while my previous booking.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your information.