You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Welcome to flight booking agency, how can I help you?

USER: I planned a trip to New York, but the snowfall in New York is heavy, so I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, I can help you in changing your previous booking. Can I have your name for checking in our data base?

USER: Sure, my name is Elizabeth Adams.

ASSISTANT: Please wait a moment to check your booking Adams.

USER: Ok.

ASSISTANT: Thank you for your information and your patience. Sorry Adams, there is no booking found on your name in our data base to change it.

USER: That's fine, thanks for your information.

ASSISTANT: Thank you for your valuable time in reaching us. Have a nice day.