Refuse to pay full deposit

Booked a vehicle via booking.com. invoice shared with tempest and discussed with tempest teller and the supervisor at cape town Airport and agree that the booking is unlimited kilometers. We exchanged the invoice on e mail and was assured that my booking is captured as per the invoice. But when I have to get my deposit I'm given 480 and they deducted the kilometers I used. Upon enquiry they were arrogant and told me it's not their problem but booking.com. when I explained to them that I was given a go ahead by their teller and the supervisor and they took the voucher with the unlimited details, they refuse to refund my money