Originally Posted by Red_bull

If you turn it to have low boost and it starts making more boost you probably turn it the wrong way. Anyway your story sound strange. But mate why don't you go to a tuner again i recommend you. They know engines and they can help you with all problems you reported. Get is sorted and enjoy the car!

Like these ppl might be able to help you!
http://www.br-performance.lu/en-lu/home/
and i already saw more tuners. Start calling and check how they react on your questions. If you notice doubt in their story onto the next