Dibby

That happened to mine, overboost. It was caused by the turbo winding up too quick (it was recently overhauled and must have been moving quite freely) and the wastegate/ variable vanes couldn't reign it in quick enough and would trip the boost sensor out.

I called the mappers and they came back, no questions asked and adjusted the map to bring the turbo in from lower revs and wind up slower. They found another couple of horsepower and smoothed out the power delivery.

Hope yours can be resolved as quick as mine. Your symptoms sound very similar to mine but can't say for sure it's the same problem ... diagnosing things off one post over the internet isn't always that reliable!