Please i urge every single person not to buy any cars from them

The worst place to buy a car. This people sold us a BMW F20. when we got home we discovered that the windshield had a small crack in it which was unable to see at the dealer as their sticker was pasted over it, the board with the cars name, model, price ,etc. We then made contact with the dealer the following moring and explained to him and he said he will speak to his supervisor and had it fixed. Ever since we have been waiting. they dont answer our calls nor do they get back to us. The more the car is packed outside and driven the more the crack speads. Please i urge every single person not to buy any cars from them. Rather go to a Renualt, BMW, or anywhere else but there.