You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Myself Rebecca Lopez. I would like to change my existing reservation because my trip was postponed. Can you help me for that.

ASSISTANT: Sure, I can help you with that.

USER: Ok.

ASSISTANT: Give me a moment to check the details for you.

USER: Sure.

ASSISTANT: Thank you for waiting. Rebecca, there is no reservation found under your name.

USER: Ok, that's fine. Thank you for your services.

ASSISTANT: You are welcome. Thank you for contacting us.