You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I want to change my existing reservation due to prepone of my meeting schedule. Can you please aid me in that?

ASSISTANT: Sure, I am here to help you with this.

USER: Thank you.

ASSISTANT: Can you please provide your name to check your reservation status?

USER: Margaret Harris here.

ASSISTANT: Margaret Harris, there is no active reservation found under your name in our database.

USER: Ok, not an issue. Thank you for checking.

ASSISTANT: Thank you for contacting us.