Faulty cars

I bought a Kia Sportage, I made the payment, and within 932km to be exact, the cars engine failed, now they are not answering my calls or returning my mails. The only fault on the car that was disclosed was a cracked windscreen, which i replaced before the car left JHB as they told me that because it was a cash sale, that they cannot replace the windscreen. I made the EFT payment on the 13th of January 2021, collected the car on the 14th of January 2021. The engine failed on 24 January 2021. I am not getting any feedback whatsoever, after trying to call them numerous times