You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I would like to change my planned dates, please help me in changing my existing reservation.

ASSISTANT: Sure, I am here to help you. May I know your name?

USER: My name is Sharon Clark.

ASSISTANT: Sharon Clark, I did not find any reservation by your name in our database.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: You are welcome and have a nice day.