Non Disclosure of engine block change upon selling car

Aug 2016 bought a Subaru WRX Sedan 2011 model directly from Subaru Cape Town. I thought they were a reputable dealer. This is my third Subaru to own. Two i bought privately and had no problems. The third my son saw at Subaru dealer so i thought okay, i will buy it although pricey for the year model. The Salesperson Mr Derron Swart did not disclose car had an engine block changed and according to him the car was good had it services on time. A year later many problems occurring although car serviced on time. First issue October car went for major service and oil leak found although no oil deposits on my paving, I fixed that problem. November suddenly engine light on, cruise control flashing and traction control. Sent back to Subaru they say 4th cylinder compression low and need to send to engineers. I was very angry about the performance of the car so i spoke to workshop manager. During our conversation he states the car had an engine block changed in 2015. I was even more angry and I said when the salesperson sold the car, he did not disclose that information to me. I requested service history of car and went to Consumer Protector Office in Cape Town to lodge a complaint. Subaru Gauteng refuses to engage in dialogue about the car and says i must refer case to MIOSA . Currently i have to pay R50000 to repair the car. I am utterly disgusted that Subaru employs such **** of Sales Person like Mr Derron Swart who is currently working at Thorp Subaru Plumstead. I am even more angry that Subaru refuse to engage to resolve the problem of car.