Can't find any fault code info for C012b and possible turbo issue.

We've got a vw Touran 2.0tdi and it needed a new turbo last year after the nut came off the shaft on the old one and destroyed the turbo. I got one from turbo technics To get their two year warranty.

I've never felt it really boosted properly after that with little low down torque. A couple of days ago an Emissions Workshop warning light came on. I have a Shark sts unit for my Octavia so plugged that in but the only code that showed up was C0076 which seems to be something to do with traction control. I took the car out and the light went out. It has come on again today for my wife and she said the car lost power and was struggling to accelerate. I tried the sts again and it showed C012b but I can't find any mention of that code anywhere. I used to have a vag com cable but sold it so can't run it on that. I had done some of the live logging on it when I had the cabe and one thing I noticed was that requested boost and actual boost were very different, actual boost was much lower. Only thing is I don't know if that is normal or not so it didn't really help me.

Just wondering if anyone has come across that code before or has any ideas about the turbo?