Engine damage caused by broken tipping levers???

Hello everyone, I have a little bigger problem, can you help me? I drove to my workshop 14 days ago because my Audi spewed white smoke from the exhaust. The workshop said, white smoke = burnt water. So the test was started. It was assumed that the cylinder head seal was over, so repair. When the cylinder heads were down, it was found that several tilting levers were broken at the intake valves. According to the workshop an engine damage. But I had driven easily 20,000 km with the broken tipping levers and with a little luck I could drive another 20,000 km with the engine. (Can that be? I didn’t have to notice anything? Unround turning of the engine etc….?) The workshop recommended to install new cylinder heads, I agreed. Now the vehicle is repaired, has 2 brand new cylinder heads and I have a bill in the amount of 5,000 euros, which I (yet) did not pay. DEN: The vehicle squalts So I went to another workshop, which immediately realized that the smoke is burned oil. Now it is assumed that the turbocharger is defective. Sh… I already turned on the lawyer, do not see to pay 5,000 euros due to a misdiagnosis, especially since according to the workshop a renewal of the cylinder heads would not have been necessary. What do I do now? Do you have experience? Can you tell me something about the broken tipping levers? How likely is it that the turbocharger is really defective? Because performance has the car without end. Would I be very happy about assistance, sorry for the novel. Vehicle data: Audi A4 Avant 2.5 V6 TDI Km-Performance: 167.800 Built: 1998 Model 1999 You can also call me: 0179/3267438 Bis denni, Frank