Bad business

Hi my name is busisiwe Nkosi. Last year july I bought a taxi from SA taxi. The taxi was in double registration if I go to license department to grab a number plate I can't because of double registration. 2 this year I take the taxi back to the dealership. Because I use it No number plates no ****s . Now they busy send me a message of arrears. When I ask a letter of volunteer sarend they refuse . They change the engine and they did not tell me or make a Clarence it mixed but 28 February I take the car back. I want to know what must do. Because one of the guy at collection they insulate me the name is Nhlanhla