Pay back my deposit money

I hired a car through MOMENTUM as a courtesy. I paid R2000 when i collect the car. They were supposed to pay back that R2000 when i return the car in a good condition with full tank. They pay back R1377 , The did not say anything about paying back money for tollgates and Etoll . I am paying Car insurance every month with Momentum and courtesy car is part of my package. I want my money back . thank you