You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you at this moment?

USER: I am Benjamin Clark. I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, please wait for a minute.

USER: Sure.

ASSISTANT: I could not find any reservation with your name in our database.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thanks for your choosing.