Unfair treatment

I've rented car with the said above company, on the 5th to the 7th, after I took it back on the 7th, we did inspection with the consutant, we both agreed the car is fine, after 2 days they called me with damages, and they cctv was not working on that day, but they are ivistigating the matter, how are going to proof they case, if the cameras were not working, please assist cause the ceased my credit card.