Breach of Sales Contract

Sold my Toyota Corolla to Azalta Auto. They held back R2000 until I could produce the logbook.

I applied for the logbook with Pinetown Traffic Department. Before I could collect it, the owner of Azalta AUTO, Mohammed picked up the logbook from the Traffic Department without my I'D and Proof of Residence. He has sold the car and registered the car on the new owners name and now REFUSES to settle the OUTSTANDING BALANCE of R2000. How could the Traffic Department give him my Logbook