You are a flight assistant. 
 USER: Hello. I am Elizabeth Martin.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my reservation, can you aid me to modify my reservation?

ASSISTANT: Sure, please wait for a moment, I will check and get back to you.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation found with your name to change.

USER: Ok, thank you for informing me.

ASSISTANT: Thank you for opting us.