You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I made a reservation for the morning  flight to visit Washington but now I want to travel in the evening flight. Can you help me in changing my reservation?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Sure, I am Timothy Walker.

ASSISTANT: Sorry to inform you that there is no active reservation on your given name.

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

ASSISTANT: Thank you for contacting us.