rental car damage

What is the name of your state? NJ
Hello, I rented a car from Avis in NJ and drove it to Montreal, Canada. I found some "minor" damage to the front quarter panel the next morning. (car was hit overnight while it was parked on a street). I drove home without reporting it in Canada (did not know what to do in another country and the damage was minimal. I reported it to Avis and they told me I'd be contacted. I waited about a week and didn't hear anything so I contacted Avis several times to find out what the status was and that I needed to get the estimate to my credit card company (my CC covered rental insurance). I did not get any response and figured I was off the hook but 2 weeks ago (7 months later) I got a call from a 3rd party collections (total fleet solutions). They asked for my insurance policy number which I did not give them. I asked them to fax me the estimate. They did it was $1100 estimated damages, $100 administrative costs, and $270 loss of use($1500 total). The vehicle was not in very good condition to begin with and was a low end vehicle). I'm not completely unreasonable and think I should get off without paying anything but they are definitely trying to rip me off. I'd assume I'll have no problem negotiating a few hundred dollars off, but I really don't think I should have to pay anything more than $500 if that. Unfortunately I did not document my calls or take pictures of the vehicle. I have not responded yet. If you have any suggestions, please help! Should I tell them to take me to court?
Thank you!!!!