Rip off mechanic on wrong diagnosis of the car problem

Gawie Steenkamp took in a family car and replaced the auto transmission box and claimed he replaced the clutch plate as well but auto gearbox do not have such. He charged over R20k. The car still had problems. He took it to an auto Electrician who identified the problem as a TCM unit meaning the job he did and charged for wasn't necessary. He just does not want money to pass him by. Now he is demanding R15000 be paid to the auto electrician which would bring the cost to well over R35000 for the Ford Ecosport 1l 2014 model. He is refusing to bring back the car and we are saying he misdiagnosed the problem on the car. He claims he is sequestered but we have his voice notes claiming he is busy with clients. His number is 079 543 4511. He took advantage that the car belongs to a black lady ignorant of mechanics now he is try to milk her dry. He lies and contradicts himself on the messages he sends out in my possession.