Touran Motor 1.4 TSI engine damage at 77,000 km ==> 8,000 € need your help!

Hello, I’m done and I need your help. Our Touran model 2013 has 77,000 km of engine damage. With 2 cylinders the piston is kaput and accordingly the cylinders. The engine was normally running but only management lamp was on and the pressure on the cylinders was not correct. The total cost is at 8,000 € for an exchange engine. Service was made at 15,000 km (at VW) at the gas station at 70,000 km. VW does not want to grant any culant because 1) car 5 years old 2) service was not or at the wrong place. Oil was always in there however. However, for me it is a production error. No service could have looked into the engine and could have seen that 2 pistons are defective. Do you have any suggestions to do anything? Are there companies that exchange such an engine cheaper and make sense to reconnect at another VW location? Are there any other options? We live in the area of Bonn. Many greetings and thanks! Gregor