Alleged damage to keep deposit

I recently had to have repairs done to my car. Thankfully my insurer provided me with a rental car from Europcar in Pinetown. The woman who did the inspection before i took the car looked for scratches and dents, but nothing else. When i returned the car, it was noticed that there was a crack in the rubber below the bumper (Something not inspected when i took the car). They then made me fill out an incident form and told me that it would effect my deposit. I tried to tell them this was not inspected but they seemed quite determined to pin this damage on me. Later on i realise that i had a picture of the car on the day that i collected it and it clearly showed that the damage was there when i took the car. I called Europcar and informed them of this and emailed the picture to their branch manager detailing the situation. I also informed my insurer of this unacceptable situation. It's been a week and i have had no feedback. I believe they just use these things to **** people out of their deposits. If this is what you do for a living, surely you should know how to inspect a vehicle properly and not prey on customers. I have since called and was told that they were investigating the situation and would get back to me. They still have not