You are a flight assistant. 
 USER: Hello. Benjamin Thompson here.

ASSISTANT: Hello Benjamin, welcome to ABC airline agency. How may I aid you?

USER: Suddenly my friends changed the trip plan.So I want to change the reservation. Can you please help me for that?

ASSISTANT: Sure, please wait a moment to check your previous reservation status and I will get back to you.

USER: Ok.

ASSISTANT: Sorry Benjamin, there is no previous reservation available in your name in our records.

USER: Ok, thank you for the information.

ASSISTANT: Ok, thank you for reaching us, have a great day.