A problem seen several times a day is the troublesome VNT turbo with its stuck waste gate due to excessive carbon build up.
Central Turbos can refurbish the troublesome half of the turbo instead of the whole unit providing the rotating part of the turbo isn't noisy or smoking.
The team carefully remove the rotating core (CHRA) and fully strip and recondition the VNT assembly, refit your CHRA, along with a reconditioned actuator, then test for operation. If you leave your vehicle with the team for this procedure, they can normally turn this job round in one day*, that's removing, stripping, rebuilding and refitting your turbo, along with the normal 'prep work' involved and any fault codes erased.
* Applies to most of the VAG group, some Fords and Vauxhalls, please ask for details.