Enterprise Rent-A-Car claims we broke their windshield? Littleton, Colorado

I apologize that this is a long story, but I wanted to detail my entire experience with Enterprise, and my general displeasure of dealing with them, even before receiving a notice in the mail that I had "damaged their vehicle". 

In September 2011, my wife and I were driving to get breakfast when we got rear-ended at a red light.  The other driver gave their insurance information and their insurance set up a repair shop and rental car for us.  We had no choice as the car rental company chosed was a shady looking Enterprise rent-a-car location off a major road.  Since I work and my wife stays home with our baby son, we needed to have a car available if she needed to run any sort of errands.  The car was supposed to be fixed within 2-3 days, so we figured we would keep the driving to a minimum.

The day came where I needed to drop off the car that was rear-ended, and my wife had opted to fly to New York with her father to visit her sick grandmother.  She had called Enterprise trying to verify that it would be okay if I were the one to pick up the car, but we never were able to get an employee to call us back.  The morning of the rental pick-up, I had called to get a clear answer on if I could pick up the car, as the agreement was made in my wife's name (it was her car that was hit at the red light).  After waiting on hold for 15 minutes, the Enterprise employee finally took my call.  I asked my questions and instead of a response, he told me that he was very busy and would call me back within 10 minutes.  After waiting a half hour, I left to drop off my wife's damaged car at the body shop still not sure about if I would be able to get the rental.  I was around 3 miles away from home and I needed to either get the rental car so I could drive back quickly, or run home so I could get to work in a timely manner.  At 8:30, I dropped off my wife's car and informed the auto shop that I was waiting to hear from Enterprise about getting the rental car in my name.  The lady at the auto shop called Enterprise for me and they arranged to "pick me up", like their commercials say.  I thought to myself "maybe this will turn out all right". 

A representative from Enterprise came and shuttled me to the car rental location.  I figured that there was only one person in front of me, so I wouldn't have to wait long.  Time was starting to become a factor, since it takes me approximately 30 minutes to drive to work and I didn't want to show up too late.  After close to 20 minutes of waiting for the representative to help the lady in front of me, it was finally my turn.  When the clerk asked for my credit card information, I was leary at first since I didn't want to have anything to do with this company.  We had used another rental company here in town before that I was very pleased with, and I wasn't looking forward to dealing with a location that I didn't have much information about (my fault for not doing more research prior).  I really did not want to be charged for anything, since this was a situation I did not want to be in.  I gave my information, found out that I COULD rent the car in my name, and figured everything would go smoothly from this point. 

Because the clerk was taking so much time, several more customers had come in through the door needing their own assistance with picking up/dropping off rental cars.  I could tell my clerk was overmatched for the amount of work that was building for him, so he rushed me out to my car.  He walked around the car, noting that there was no damage to the exterior.  He briefly showed me the drivers seat and where the necessary controls were, and gave me the quick version of their personal insurance coverage.  Since I refused to pay for this rental car (the insurance company of the driver who hit us should cover it, in my opinion), I opted not to take the insurance.  It would only be a few days, right? 

I looked over the paperwork and the clerk ushered me to sign so he could get with other customers.  I was in my own hurry to return to work, and so I opted out of the Enterprise coverage and signed the work.  I did NOT do my own inspection (huge mistake, I've learned, if you're going to rent from a rental car company that you're not familiar with, or any for that matter), much less take any pictures. 

I get into the car to drive off when I realize that not only is the car dirty (gravel and dirt on the floor, small bits of trash in the back seat), but that the gasoline tank was empty.  I walked in and notified the clerk, who asked the other representative (the one who shuttled me over) to accompany me to the nearby gas station and fill up the tank.  We drove over to the gas station, where the representative filled up the tank halfway, paid for the gas, and instructed that we drive back to the rental location so I could drop him off.  I do so, and then head home.

Once I get home, I noticed something:  the rear seatback was pulled forward (likely so that someone could get in and out of the very back seats) and I couldn't reset it to it's normal upright position.  I needed to install a car seat, and was hoping to place it in the middle of the car, as it's reportedly the safest position.  I was resigned to placing it against the passenger side window since the seatback was stuck and I didn't want to risk breaking anything.  I likely should have called the rental location, but figured that it might not be a huge deal, as it was currently a monday and our car was supposed to be fixed by wednesday, and my wife was returning wednesday evening. 

On wednesday, I got a call from the auto body shop explaining how they were waiting for parts, and that our car wouldn't be ready until the following monday.  We ended up having to use the rental car as a means of transport for my wife, since I was gone all day at work and couldn't take the time off. 

The following monday came and we got a call from the autobody shop in the late afternoon informing us that our car was ready to pick up.  I came home from work and we headed down to the autobody shop in our rental car.  They informed us that we could leave the rental car with them and Enterprise would come retrieve it.  I left to make sure the gas tank was filled to the same amount I received it in, returned to the shop and dropped off the keys with their front desk.  In retrospect, I probably should have waited for the Enterprise representative to arrive.

A few weeks later, I received a very generic looking letter explaining that we had caused damage to the vehicle.  There was very little information on this letter, except that it asked me to return it with full insurance and credit card information.  I was very upset upon receiving this letter, since we did no damage to the vehicle and returned it in arguably better shape to the autobody shop (it was clean this time, WITH gas).  I notified my insurance company and they said they would look into it. 

A few months had passed and I recently heard from my insurance company who said Enterprise claims we damaged the windshield and that it would cost us 149 dollars, which is under the deductible.  I was relieved in a way that it wasn't some outrageous rate like some other claims I've seen around the internet, but still not happy that they would try to make me pay something like this.  A few days later, I received another letter from Enterprise with the true amount: 149 for the repair, and an additional 50 for "administrative fees".  The letter did include a very generic looking "bill" from an auto glass company, with no details anywhere on the letter of exactly what damage was done, or any proof that I had caused it.  No pictures, no descriptions, nothing explaining what happened.  It was just a letter basically saying "pay us".  I was already hesitant to pay the 149 for the repair, much less an additional 50 dollars for administrative fees. 

I won't be taken advantage of, and I intend to dispute this for as long as it takes.  Why should I have to pay for damage that they claim I caused, and they never once give me ANY information on what the extent of the damage was, or any proof of it whatsoever!  This won't be the only website I report this to, and I advise anyone who needs to rent a car to STAY AWAY FROM ENTERPRISE!!