Sold my car without my knowledge

Hi<br> I towed my car in for repairs at Car Service City Linden branch about a year ago. They quoted me R25 000 for the repairs for which I paid a deposit of R8 500. After a few days they discovered that I needed to replace the gearbox as well but I advised them not to go ahead with replacing it & that I will be buying the gearbox myself since the price the price quoted was too high. However, due to financial problems I was not able to come up with the rest of the outstanding balance. As soon as gathered the money, I called them on the 6th of Jan 2016 to inform them that I want to come and collect my car and pay off the balance but I was informed that they had sold my car.<br> I was never contacted about this decision. The branch manager informed me that the garage had started implementing a policy to sell vehicles that have stayed in the garage for more than 6 months. When I towed my car to the garage in the first place I was never told about this policy nor I was informed about the policy change.<br> I was neither contacted nor given a chance to pay off the balance outstanding and collect my car before my car was sold.<br> Are they allowed to this and is this legal? What can I do to get my car?