Competition BMW of Smithtown Sold car certified that was in an accident and did not disclose after clean carfax report provided St. James New York

I bought my car off lease from Competition BMW. The car had a clean carfax when I purchased the vehicle. When I went to trade in the vehicle I was informed that the certified (CPO) car with in a three car collision that was not reported by carfax until several months after I purchased the car. I went to the dealer to find resolution. They ran a paint pen around the car and advised it had never been in an accident. Then they called me and told me it was in a minor accident hit in the rear and we discussed the cost differential to rectify the now blemished carfax on my vehicle. I never received a call or email back from the dealer (sales manager, GM, owner) after that conversation. I escalated this issue to Germany and they sent it back to NA for further investigation. I still cannot get a reply from the dealer and my services and sales experience as a client was extremely poor all around in my opinion. They offered to buy my car back or take it as a trade-in but no idea what "fair market value" means retail or wholesale. They offered a letter which they did not produce. They are now pretty much non-responsive to me, the client/customer. This has been the worst car buying experience I have ever had from a dealer in my life. Weather the car was in a major or minor accident, it was reported by the lessee to insurance and claimed which puts it on the carfax. The dealer logic is that it wasn't a major accident which is irrelevant to me. The fact is that there is still now a dirty carfax and the car is worth less. They directed me to carfax who did not reply and the dealer's remedies are not viable for me. They also offered 10% of the wholesale value of the car and after initial negotiations no reply. I feel that the during and after vehicle purchase experience was 0/10 for me in my opinion. It is hard to imagine that this is how they view customer care and satisfaction. I would not return to this dealership.