Worst service car service city centurion

I have had the worst experience with car service city centurion, my car was overheating and took it in they gave feedback and said it was radiator leek and it will cost me 8k, i agreed on the fee now for time of collection they they've picked up another problem my car will not be drivable but i still need to pay the 8k. So basically i drive my car there and my car is not driving and i need to pay 8k...