Incorrect Bill Sent

I'm having some issues with National Car Rental. I had rented a car from National Car Rental from 7/22/13 - 8/6/13. Before I took the car off the lot at the Norfolk Airport, I thoroughly inspected the vehicle to ensure that there were no damages on the car to protect myself financially. As it so happened, there were some pre-existing damages to the 2013 Toyota Venza SUV that I was assigned to which surprised me because I've never seen those kind of damages to a rental car before. There were deep scuff marks and scratches to both front and rear-end bumpers. Not knowing what else to do because I've never been in that situation before, I contacted a National rep to take a look at it. Unfortunately, the young rep decided to just initial the damages that I notated and initial at the end of those remarks on the rental paperwork. Not thinking much of it, I walked away with that, thinking it was better than nothing. A few weeks later, before I was due to return the car on August 6th, I noticed some damage to the passenger side door of the car that I haven't seen before. Guessing that maybe it was caused by a hit-and-run accident by a bad driver while parked in a public street, I thought it was too late to report it and find the driver who had side-swiped the car. I decided to just return the vehicle and pay reasonably for the damages that that driver had caused to the middle of the passenger side door. That was unfortunately, not the case when I received the final estimate in the mail in September 2013. While National was grateful in congratulating me on my honesty and sense of responsibility in regards to owning up to the damages, it also is on the other hand, charging me for previous damages done to the car by other car renters who had the car before me. I had emphasized the damage done to the car before I took it off the lot and even showed them the rental paperwork to prove it. In the end, it seems like National is charging me for everything. And it looks like that's what they did and backed it up with so-called evidence with black-and-white photos of ALL the damages done to the car, possibly since the car's been loaned out. $1,504 is a lot of money. Who has that easily lying around? National, of course, never responded to my request, through the BBB, for redoing the bill for $1,504.57 which includes ALL the damages since the car was first rented out. I just got another bill in the mail recently and it said the exact same thing. I contacted the local National office in Norfolk, VA by the airport and a rep responded back by saying that National will go ahead and collect the damages. NO ONE is making an effort to send me the RIGHT bill amount. Until National fixes the bill, I will seek find ways to fight this whether through Small Claims Court, lawsuit or a lawyer. ALL I want is the correct bill. It's not like I want to escape from paying for any damages.