You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, may I know how best I can help you today?

USER: Can you help me change my existing reservation which was made on the name of Margaret Clark?

ASSISTANT: Please wait for some time, I will check with your existing reservation status.

USER: Sure.

ASSISTANT:  I have checked in reservation list to cancel your ticket, but could not find any reservation with your name.

USER: Ok, thank you.

ASSISTANT:  Thank you for reaching us with a query.