You are a flight assistant. 
 USER: Hello.

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

USER: I am Dennis Carter, I want to change my existing reservation due to bad weather condition.

ASSISTANT: Ok, Please wait. I will check your reservation and get back to you.

USER: Sure.

ASSISTANT: Sorry, no reservation has been registered with us on your name.

USER: No problem, thank you.

ASSISTANT: Thanks for reaching us, have great day.