Radek- I would be pleased to answer your question or atleast try to. Please make a New thread for that topic, so we do not make this thread confusing.

I just noticed the tense of the problem. It says he used to beable to turn off his boost controller, and it would appear to revert back to wastegate spring pressure(I'm assuming his wastegate spring is around 10-12psi)
And now it would appear even when turning off the unit something is still bleeding off the pressure.Possibly just got a hole in your vac. lines between your boost controller and wastegate.

Easiest solution would be to borrow a MBC like Jordan said with new VAC. lines going to and from it. And if that fixes it, then to fix your other controller you should run new VAC. lines to and from your current boost controller, and see if that fixes it.