2012 Mercedes C220 W204 P0299 Fault: Low Turbo Boost & Limp Mode Solution

I own a 2012 Mercedes C220 W204 with twin turbo (2.1L BorgWarner turbo) and am currently experiencing fault code P0299, which indicates low turbo boost pressure. The issue primarily occurs when driving uphill, causing the vehicle to enter limp mode. After turning off the engine and restarting it several times, the car regains normal power and the engine warning light eventually turns off after a few starts. I've already inspected the vacuum system and found a leak in the air inlet pipe—this has been repaired. I also had the DPF and EGR valve cleaned using chemical treatments. Most of the error codes have cleared, but P0299 still appears intermittently. I’ve replaced several sensors, yet the problem persists. I've consulted multiple turbo specialists, but their diagnoses lack confidence. While I’m open to replacing the turbo, I'm unsure whether this would resolve the issue. My current hypothesis is that either the turbo actuator or solenoid is stuck, or the turbo itself may be faulty. Key questions: - Where can I purchase spare parts for the BorgWarner turbo on a 2012 C220 W204? - Is the actuator component replaceable? - Are there available service manuals, schematics, or technical data to allow me to recondition the unit myself? As a combustion and mechanical engineer specializing in heating pumps, I am confident in my ability to perform such work. However, I'm struggling to locate official documentation or detailed diagrams for this specific model. Any insights, experiences, or recommendations from owners who have faced similar P0299 issues? How was it resolved? Thanks for reading and sharing your knowledge.