just to clarify earlier in thread you wrote
Boost pressure was at .7mBar and dropped to about .5 when throttle was applied. Desired boost pressure was 1mBar at idle and rose to about 1.1 when throttle was applied
im thinking you meant
desired at idle 1001mbar actual at idle 1007mbar or 1070mbar?
desired when revved 1100mbar and actual 1005 or 1050mbar?
it seems strange that the boost pressure dropped when revved even parked up no load when reved the turbo usually makes more boost and if I remember right on std turbo is usually slightly above desired boost.
if its going in they could check the turbo is not seized or jammed by removing the turbo inlet pipe and having a feel in the compressor housing that it spins freely.
also in that area worth checking the inlet pipe is not blocked , or maf blocked or air filter blocked.
if you have ecu scan , did you ever do a maf reading ?
they could split exhaust at turbo on the v band to see if revs better ie blocked exhaust/cat?
and you havnt confirmed if the antishudder valve at the inlet to the manifold is operating correctly , this bit
viewed from rear of engine , should be opening with engine on and closing as engine shuts down.