I've heard about your car from other people (not Yavuz). I think if anything, you have learnt about dodgy back yard mechanics and dodgy ebay car parts. Unigroup do tuning, not mechanical work. With so many things wrong with your car and no mechanical work being done, they never had a chance.
In my opinion, if you want diagnosis of difficult/weird problems, see Mark at Hills Motorsports. If you want a solid tune and your car has nothing wrong with it, go to Unigroup. If you just don't know and need the whole thing methodically checked over, UAS. Of course each of these has other things they can do/are good at. These are just the things I think they do very well.