Pohanka Lexus of Chantilly

I gave only star as I could not give zero or negative star rating. I bought 2011 RX350 from Pohanka Lexus on 12/10/2017. The Carfax Report showed clean record without any issue. Two weeks later, I got second Carfax Report pulled by another Dealership and to my surprise, the second Carfax Report is showing one accident that happened on 2/11/2017, ten months prior to my purchase. It also mentions in the report that "Carfax began reporting this information on 12/12/2017". When I contacted Pohanka Lexus, the Manager said when the vehicle was sold, the Carfax Report was clean, so I have to bear the burden of loss due to a ten-month prior accident. I have been asking them to take the car back as I do not want a vehicle with an accident. They refused. No fault on my part but I am stuck.