deposit return

I hired a car for 3 days 25-28 june, 17:55- 17:55 i returned the vehicle on time before my flight to cptwn, which was 18:50. I could not wash the vehicle as it was raining in free state bothaville over the weekend and could not refuel the vehicle as i did not have the time on my return. The vehicle was checked upon my return for damages and all was in order, i phoned on tuesday to ensure all all is in order and was informed i will get my deposit back within 7 days. I paid deposit of R4567.00 and on wedesday 01 july 2015 today i receive and amount of R2236.56 in my account from tempest, and i phoned them immediately and spoke to brian, and was transfered to account department and spoke to Patricia, i requested and invoice so that i can see where 51.03% of mmy deposit went to, because yhe cost of refuelling a 40 litre car which i left at 1/4 and most expensive vallet of R400 are +/- R1000, was told the invoice has not been done i will get it in 3 days, i cannot understand how the money is paid back and i have yet received invoice to see what ive been charged this chunk of money for. Before i go to ombudsman what do i do...