2 Days Rental Charge after Returning Car

Was in an accident and received a courtesy car from Europcar on 10 July. Received a SMS on 5 Aug stating I need to return the car on 9 Aug before 15:00. I phoned Europcar callcentre and asked whether I can drop the car of at their Centurion Branch as it was a Sunday and the Centurion branch is closed on Sundays. I was told yes, I can just leave the keys at the Protea Hotel reception, which I then did on 9 Aug. On 11 Aug I received a phone call from a Europcar agent stating he wants to come and collect the car as 10 Aug as a holiday. I told him I already dropped the car of at Centurion branch. I was then charge for the two extra days, 10 and 11 Aug, plus the petrol to drive the car from Centurion to Woodmead? Not acceptable. And now it will take another 3 days to resolve the query?