You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I am Rebecca Hall, I want to change my reservation due to postponement. Aid me about it.

ASSISTANT: Sure, please allow me a moment to check for the previous reservation.

USER: Ok, sure.

ASSISTANT: Rebecca, there is no reservation found under your name.

USER: It's ok, anyway thank you for the help.

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