You say the last turbo 'blew'. Turbos don't normally break unless they are starved of oil or coolant. There should be an underlying problem behind the failure.

'Turbo pressure regulation fault' means the wastegate is failing to operate correctly. The engine is gutless because the ECU is witholding fuelling to protect the turbo from over speeding. Your mechanic needs to check the N75 valve (controls the wastegate) and the wastegate itself for correct operation. This is a fairly generic problem that a competent mechanic should be able to tackle...

Garrett are a widely respected turbo manufacturer, their turbos are highly regarded There's no reason for you to question the failure of a turbo-I only ask the qustion because, from experience, any lack of engine performace is blamed on the turbo and the root cause usually lies elsewhere.

It is not necessary to strip the engine in order to access the turbo-the turbo is attached to the exhaust manifold-although it can be tricky to raccess in tight engine bays.

The problem of wastegates sticking closed and triggering a fault which effectively puts the engine in limp home mode is very common in turbo diesel cars. It should be easily rectified by ensuring that the turbo wastegate and it's control are functioning properly. Off hand I don't know if your turbo uses a pneumatic or electronic wastegate control (although the principal is the same). It should be a cheap problem to fix.