You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure. Please could you let me know your name?

USER: My name is Kimberly Hernandez.

ASSISTANT: Please let me check details with your recent reservation.

USER: Sure.

ASSISTANT: I regret there is no reservation by name Kimberly Hernandez. Thank you. Have a nice day!.