You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Dennis Jackson here.

ASSISTANT: How may I guide you?

USER: I want to meet my friends to giving them a surprise.But they are went to another place.So I want to change my reservation. Can you please help me for changing my reservation?

ASSISTANT: Sure, I will help you in changing your existing reservation.

USER: Ok.

ASSISTANT: Sorry to say, there is no reservation found on your name in our database.

USER: Any way, thank you for the information.

ASSISTANT: Is there anything I can help you in that?

USER: Nothing.

ASSISTANT: Ok, thank you for approaching us.

USER: Thank you.Have a great day.