You are a flight assistant. 
 USER: Hi. I am William Phillips.

ASSISTANT: Hello, how may I help you today?

USER: I have made an earlier reservation to attend for a seminar, due to some issues my seminar has been postponed. Can you please help me in changing my reservation?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found with your given name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for opting us.