You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How I can help you?

USER: I want to change my existing reservations. Can you help me?

ASSISTANT: Sure, I will be happy to help you. Can you provide me your flight details?

USER: My new reservation departs from Dallas & Fort Worth, TX-DFW and returns from Dallas &Fort Worth, DFW.

ASSISTANT: Can I have your name please?

USER: My name is Robert Perez.

ASSISTANT: Thank you for providing your name. Sorry to inform you there is no reservation found.

USER: Ok, Thank you for your valuable information.