Secondary air pump problems are common with the new VW's with that system. The kombi valve sticks or fails and moister from the engine exhaust flows back into the air pump, filling it with water. Which then fails.
Volvo's had the same problem.
Unfortunately a new valve and pump are needed to fix the problem. If you can find good used part, you might be in the same predicament sooner than later. OR at least get a new valve. You may be able to find a good pump.