You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you?

USER: I am Stephanie Mitchell. I would like to change my reservation to new travelling dates, would it be possible to change it?

ASSISTANT: Sure, give me a minute for checking. Sorry, there is no reservation found under your name.

USER: It's ok, thanks for your information.

ASSISTANT: Thank you for opting us.