You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I assist you today?

USER: I want to change my existing reservation due to sudden change of my travelling dates. Can you help me out in changing my existing reservation?

ASSISTANT: Sure, I will help you in changing your reservation. Let me know your name please?

USER: I am Justin Miller.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, we have not found any reservation with your name.

USER: Ok, not a problem. Thank you for aiding me.

ASSISTANT: Thanks for approaching us.