How frequently is the oil and filter changed in your Seat and how many kms are on the odometer? The reason I ask is that VW's recommended long oil change intervals cause problems in US operated Audis and VWs. This is partially caused by US oil companies crude oil stock that is often "not good" and is actually known as "sour crude ". Do you know for sure the correct oil and filters were used for Seat's engine? I have worked on some Audis that have malfunctioning camshaft adjusters but are a different design than your 24V 2.8l VR6 so my experience is not quite relevant in your case. Was the camshaft timing also checked with VW special tool no. T10068 inserted into the camshaft end slots or just by the inspection in the sensor openings?