Hii guys, I've got a problem with my A6. I'm accelerating full throttle and the car feels like it's styfiling and is going no where. Feels like no turbo at all. Went to do a diagnostic by a friend tonight and got these codes:

Fault Code 1: 17956
Description:
P1548 Solenoid valve For charging pressure
control- N75open circuit

Fault code 2: 17887
Description:
P1479 Brake vaccum systemMechanical malfunction
Status:
/SP

Anyone could help with this? Also, can anyone give me a website to order Audi parts? I live in Trinidad in the West Indies and they are very expensive here. I recently changed the Transmission control unit on the car and they charged me $21,000. 11 of our dollars is worth one of yours, can you guys help a brother. Thanks alot, first time poster here. Had the car from day 1