Nelspruit We Buy Cars did me dirty

I bought a Range Rover Evoque last year in December at We Buy Cars in Nelspruit branch. They sold me a broken car with no service history. Since i bought the car iv been fixing it until i decided to sell it back to them on the 11 of October and they told me that i have to fix it first. How because they sold it to me broken but now they want me to fix it? Hello Peter help me resolve this issue