Wrongful billing

On the 5th of January 2016, I rented a car from Avis group. I checked the car with the Avis guy, who noted that there was a small dent on the car which he noted on the contract. When I returned the car, we did the inspection again and the Avis guy asked me about the dent and I explained that the dent was there when I took the car and it was noted. Unfortunately I couldn't find my copy of the contract but he assured me that they have a copy and he will check it on his copy. I then send an email when I received an sms explaining the charges of the dent. On the email I explained what happened and requested a copy of my contract which I haven't received. To my surprise, today my credit card was debited with the the damage charges which even caused my credit card to be over my limit which will also add bank charges to my credit card. I need the matter to be addressed and settled.