Overcharging

When I collected my vehicle the Assistant was great. I received a rental agreement which showed that i paid a deposit and the rental agreement amount. I was a little surprised to see that the petrol was not full and on returning the vehicle I notified the attendant. I have now received an invoice which should a refuel charge of R534 for only 250km travelled. The invoice does not reflect the correct deposit paid and says I have an amount due of R1009.70. I spoke to Emma MAshangu who could not explain the invoice......I am very frustrated and feel **********.