I had a similar thing last year, had been travelling at for 30mins or so, and had a stint of 100/110mph for 10mins and then lost any sense of acceleration. Felt like the turbo had failed. The DSG would drop down a gear or two when I tried to accelerate and just had lots of noise. Felt like a 1.4. I then left it for several hours and took it out, and had about 80% power back. A few days later it was just about back to normal.
I had it checked for errors and turns out the turbo has shut off as it was reading as over-boosting(??). Had the error cleared and it's never returned. Do you have any temperature issues? At the same time my temperature started reading as 70º rather than 90º. I ended up having a new thermostat and sensor fitted, but never had the turbo issue again.