Anglo Auto belgravia does not value their customers

i had a very bad experience with Anglo auto belgravia, i bought a car a merc from them ,The car was R410 000,00 .i drove the car to eastern cape on the sixth day from the day of purchase,i couldn't even reach my destination, the carcass towed to mercedes benz in East london, they checked the car and said the problem on the car started 1000km before they sold it to me, Anglo auto says they gonna fix the car but they refuse to give me another merc while they have the car that i purchased from them, they said if i want a loan car i must pay deposit and i refused, i don't want their car anymore plz help