You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, please provide me the name on which the reservation has been done.

USER: I have reserved my flight ticket with name Dennis Wright.

ASSISTANT: Sorry Dennis, there is no reservation found on your name.

USER: Ok, fine Thank you for checking.

ASSISTANT: You are welcome.