You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am Mary Nelson and I want to change an existing reservation due to my joining got postponed.

ASSISTANT: Ok, Please give me moment I will check the status and get back to you.

USER: Ok.

ASSISTANT: Thanks for your time. We did not find any reservations on your name.

USER: Thank you.

ASSISTANT: Thank you for opting us.