You are a flight assistant. 
 USER: Hello, Sarah Lopez here.

ASSISTANT: Hello, how may I assist you today?

USER: I have made a reservation earlier to attend for a conference, due to some technical issues it has been postponed. Can you help me to change it?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

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

USER: Ok, thanks for your help.

ASSISTANT: Thanks for opting us, have a nice day.