Replaced Manifold Vacuum Actuator, but underboosting! Help..!

Hi All,

I have a Seat Leon 2.0 TDI FR 170 PD and I am having underboosting issues.

The car has just had it's a Manifold Vacuum Actuator replaced, but the problems still persist. Basically when driving the car, especially when in 5th at 2,000rpm I have no power and it then chucks up the glowplug light and goes into limp mode.

The car has the following fault

000665 - Boost Pressure Regulation 
P0299 - 006 - Control Range Not Reached - Intermittent
Freeze Frame:
Fault Status: 00000001
Fault Priority: 5
Fault Frequency: 1
Reset counter: 37
Mileage: 100460 km
Time Indication: 0
Date: 2000.00.00
Time: 17:58:14

Anyone shed any light on what else it could be?

Thanks