Car sold, two months later, a letter from the lawyer…

Hello. I sold my car (Mercedes C-Class, almost 11 years old) at the end of November. 7 years it was in my possession. So, car sold, and 1 month later the buyer registered… The rear brakes were stuck,he repaired it in the car dealership (MB)… 900 € invoice (back brakes+4 spark plugs+cable for candles) They also thoroughly examined the car there… quote from the letter: “On this occasion it was also noted that the wheel bearings on both wheels on the H In addition, the track and steering rods on the front axle were broken. Also the exhaust manifold seal as well as the cylinder head gasket are defective.” Excluding the liability for defects is part of the purchase contract (lecture). I wrote in the special agreements “bought as seen” And I really didn’t know that the car was as defective as they have just described… I had no problems with the car GAR… Me in lawyer has also written back some words… Yesterday came the next letter… I am supposed to pay back the purchase price + all the costs that the buyer has already paid, i.e. repair, lawyer…. And at the bottom is that the buyer is ready to keep the car for 2000 €… I have already paid for lawyer piles of money… And if in a few days the money is not there, which go to court… What should I do? I have no plan anymore…