Usage patterns
〈人〉に聞くto ask the staff member (in charge)
Please ask the attendant if you're unsure about anything.
係員が案内するthe attendant shows/guides (someone)
The staff member guided us to the venue.
〈場所〉の係員the staff member at (a place)
The station staff showed me how to buy a ticket.
係員を呼ぶto call over a staff member
Since a problem occurred, we called over the attendant.