Ridiculous charges

My Audi broke down again gear box problems second time in 12 months.... The customer service assisted us as we were in dullstroom on the way to a family vacation.... They arranged a vehicle for us to carry on with our journey however once delivered and returned I was charge all sorts of fees returning vehicle to an other rental office then damages that where not the result of our driving..... Considering that they had delivered the car from nespruit to dullstroom, notoriously bad pot holes.... I was told to give them a credit card for guarantee for petrol..... They used it for all sorts of charges(unauthorized) Have been trying to get these fees refunded for the last 2 months not assist from Audi or hertz????