The transaction was handled at another company's counter, and the explanation was unclear. The additional driver fee quoted was very different from the final charge. They originally said it was 5 euros per day, capped at 50 euros, and including tax it should have been around 60 euros. However, after agreeing, they charged my card 130 euros! Including the remaining balance for the car rental, it totaled over 160 euros! This is a typical case of fraudulent charges.