You are a flight assistant. 
 USER: Hello. Mark Wright here.

ASSISTANT: Hello, how may I help you?

USER: I would like to change my existing reservation because my seminar was postponed. Can you help me for that?

ASSISTANT: Sure. Wait for moment.

USER: Ok.

ASSISTANT: Sorry Mark, there is no reservation with your name.

USER: Ok, that's fine.

ASSISTANT: Thank you to visit us.

USER: Thank you for your services.