Poor quality vehicle and terrible customer service

I purchased a Golf 7 gti from Nissan Nigel Autocity, in Johannesburg, on the 2nd June 2018, from the 5th June 2018 I have been complaining about the faults in the vehicle and the dealership refused to help me. It came to a point where the sales person Wessie even blocked me off whatsapp and stopped taking my calls. On the 20th of March 2019 was the final straw, I took the vehicle for its annual service and it was then only determined that the vehicle had major internal faults, I am now sitting with a vehicle that is not even road worthy. The staff was only helpful in making a sale thereafter it was total arrogance and rudeness. I'm extremely frustrated, i have been taken advantage of because I was a first time buyer and a young female.