How can i fix my Stralis AS 310?

I drive a 310 Stralis truck and have had problems with EDC 2f warning light light on dash. After changing the primer pump and a plug in at the dealership the problems persist. The issues are charcterised by a loss of boost pressure at indeterminate intervals with what seems like no pattern. Sometimes the warning light comes on when the engine is running with load (uphill etc) sometimes not. To drive, the trucks feels like it has simply gone into 'normally aspirated mode' i.e. occasionally turned off the boost. I have not noticed any differences in temperature and pressure either. The dealership said that the turbo was the issue and that it would be resolved by changing it out. I was thinking 'could checking and cleaning the VGT control valve possibly remedy the issue ??

We have changed the primer pump.
diagnostic fault says DTC 10, FMI 0C, OC 001,
ACT Y when there is an issue....