CarMax — total loss of vehicle

Hello, I purchased a 2009 Chevy Tahoe from Carmax in May 2017. My truck was then totaled in Dec.20, 2017. I only had it for 7 months. My insurance paid $20189.96. I informed Carmax finance the day of the accident and told them that the truck was in an accident and I think its a total loss. The insurance adjuster confirmed on Dec.22, 2017 it was a loss. After about three weeks a check was sent to Carmax. They received the money and still say I owe a principal balance of $1357.04. I feel I do not owe that I have paid every car payment except for December 2017. The total payments I made is $2758.80 and they are not considering early pay off which that would be exactly what it is. In total, my loan was $22, 249.86 after you add the check from my insurance and what I have already paid it comes to 22, 948.76. They already made a profit of $698.90. You have your money and its paid so please remove me the late payment phone calls and take this loan off my credit. I have received several phone calls and I tell them every time the truck is gone it's totaled.