Webuycars selling cars without changing ownership from previous owner

I would like some advice, I sold my car to WeBuyCars on the 07.01.2022, my car was no licensed when I sold it to them so the reduced the sale amount which was fine. 29.05.2022 I was stopped at a road block and I had my kids with me because Metro was checking for outstanding fines. I have never received a fine before so handed my license so I could get on with my day only to be told I have 4000 rand worth of fines on my name and if a warrant was issued I would have been arrested. My kids and I were traumatized. The guy I dealt with advised me that one of the managers will call me but I must show the contract to who I am not sure and the owner of the car is responsible. However all the fines are on my name. Please help I am a single mum and not sure what do in this matter.