Dishonest car mechanic

My car engine was damaged,as a result an overhaul of the engine was conducted by Darren &Sony Mechanic specialists. Due to the price of the work I made payment arrangements with them.Fortunately they agreed and I paid the 1st 10,000 into their paid account until the account I was quoted for (R22,5000 was fully paid up. To my shock and devastation,Amesha (Darren'so wife called) to say I still owned them R8,500 for additional parts.I asked her where is it coming from,she started shouting at me and I reminded her that am still a customer here I can't pay anything without a proper explanation, she was rude.I was desperate to get my car fixed and foolish me I paid. After a week I sent her numerous emails asking her when will I be able to get my car. After a week,she responded with a number of excuses. She then said it would be ready the following Monday, the day came I followed up and I was told ooh sorry you need to pay an additional R 6,600, unbelievable conduct. Again I questioned the 3rd additional payment. My car is still is not fixed with all my money with them. The husband then sent me R18,000 additional quote for the so called additional parts. Darren threatened to tow my car outside his premises. I have reported the matter to the police, Speak out and Carter Beach, they need to be expected exposed of their scrupulous ways,They are rude and are set in their ways of taking people's money. To date no car,no money.