I got charged I don't understand and they cannot explain them to me

I rented a car for 14 days, paid for the super cover as well and returned the car with a very small dent at the back. Fine they can pull the amount for repairs but then my invoice is has all these charges that its not even clear which was the reserved amount and which ones were part of the cover. The agents can't even explain it well to me, now they tell me I should have asked at the shop for them to separate my charges so I can understand which amount is returnable. I'm very disappointed at their services and how they cannot explain the hidden charges to me.