BKD power loss

I have a 2007 Octavia, BKD 140 TDI on a DSG box with 99k Milage. 3 years ago it had a new turbo ( through Skoda warranty) for the dreaded power loss. Now it's back again but only seems to happen if I have used the engine breaking going down hill and then try and accelerate away. When it first started again I was told it was the sticking turbo veins causing the over boost pressure. They said I should give it a good thrash up the motorway near the redline to burn it off. So 5, miles no change, 10, 15 and more and the same thing happens. Yesterday it limp moded 3 times in 6 miles. Then it was going fine for a mile and the engine management light (EML) came on with engine imisions light came on. I sensed a little loss of power but no limp mode when pushed. Today still have EML but also limp mode. Will take it to my friendly independent VAG specialist Monday. Im hoping they can fix it and maybe my extended warranty with Warrantywise will come in handy?