Checking your fault codes there's a lot of issues there, even has 46 code, which is usually problem with cccu.
My guess would be that "technician" butchered the system somewhere, or someone before him, but he definitely didn't fix it up much, and the whole system is really confused now.
It might be something small, like miss-wiring or so, but what I recommended is take your A2 to a place with a reputation, as many backyard "pros" as really bad at their jobs.
I don't recommended trying to fix it on your own, it can cause even more issues.
I know it's not great reading this, I try to fix as much as I can to save money, but there's a point where you have call a professional, and this is that point, because for now the car is dangerous to drive, it might even accelerate on it's own at any time. Just take it to a garage and see what they say. Good luck.