Overcharged for slight damage

I rented a car from Avis (George Airport) on the 5th of Dec 2018. They reserved 5600 Rand from my card (this included rental, super cover insurance and a deposit) When I returned the car, I noticed there was a scratch (about 2cm long) on the vehicle. I waited for the quote to mend the scratch and Avis came back a week later saying they are going to charge me 2800 rand for the 2cm scratch. That amount is absolutely ridiculous for the slightest bit of damage on the car. To note, I also took the super cover which is the most expensive cover on the car and this did not cover this scratch. I feel cheated that I even bothered taking it out as it amounts to an extra 120 rand or so a day. That is only one part of my irritation. The second was that without warning, they deducted another 6000 Rand (which was for the rental, super cover, deposit and damages) and did not bother to release the other initial reserved amount of 5600 Rand. I am still waiting for the return of this reserved amount (this is after an entire month). In total they removed 11600 rand from my account (5600 for the initial deposit, 6000 for the revised amount with damage). All this without a single phone call.

My irritation is that Avis could have surely gotten a better quote than 2800 rand, also deducting money from an account without releasing a deposit is extremely painful. Will never use this car company ever again

PS: I am still waiting for the 5600 Rand to be returned.