Poor customer relations at Europcar

I book a holiday package to Cape Town through Kulula and the car hire was at Europcar. When receiving my deposit I realized that extra money was taken except for the fuel. I phoned them and some really rude lady told me the car was returned a day later, which is impossible because it was returned on the day stated on the contract which was also the same day my flight was booked. The more I tried to explain this to the lady the more she told me it was late. I think this is very poor service and customer relations.