Dishonest Europcar car hire.

I've recently hired a car from Europcar. Upon returning the vehicle I was billed over R600 for tollgate usage. I used the Marrianhill toll road twice at R15.50 a time and Tongaat twice at R14.50. The etag, fitted to the vehicle, didn't work the first time so I used cash yet I was still billed so much. If the Etag did pick up at the tollgate after I paid cash I should only be billed R60.00 instead of more than R600.00.