Unpaid refund of deposit

I hire a Hundai from Van Rentals Europcar thru Santam and return it on 31 March. I receive a email on 31 March from europcar that they have receive my refund form with my banking details. Till this day I have not receive back my deposit . I spoke to several people but was not able to get a refund of the R1700 deposit that I pay. It is an acceptable that I have to pay the deposit before I can get the car but it is longer than a month that they have my money,