You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: As my to attend an international conference has been postponed, and again it has to start in the next week. So can you please help me to change an existing reservation?

ASSISTANT: Sure, may I know your good name please?

USER: My name is Sandra Campbell.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, no reservation found with your name to change.

USER: That's not a big problem. Thanks for your information.

ASSISTANT: Thanks for opting us.