Trusting PC technicians can be hard, since they abuse the fact that they ''know things'' and you don't. Ended up paying 100 EUros once to a shop. They kept PC for all summer without doing anything. Still wanted the money though.
Anyways, after that we took it to a 60 y.o neighbour of ours who keeps fiddling with PCs and other devices. He just bought a new motherboard, reinstalled windows- done. Only cost us 80Euro and he slapped on a free Hard disk from his old ones
Moral of the story: Find a friend who knows IT/Hardware/Electronics - and make sure he doesn't hold a grudge against you!