Europcar Ripping people off

I rented a car from Europcar, the car came with an e-Tag which I didn't mind ofcourse. Yesterday I receive a cal from Makhosazana Sibiya from Europcar telling me that over and above the R1450 I paid as deposit when I took the car, I still owe them R531,77 in Toll fees. I requested the invoice and how they calculated the money and indeed she emailed me the documents.

To my surprise, though the statement is written 20% Rental car discount, they actually add 20% to all the original toll prices and then also goes a step further by adding 15% Vat, which mind you, is already accounted for in the original toll prices... Is this not ripping people off though?