Sorry to hear about the problems man.
I know exactly how you feel.... sometimes it seems like they just don't care about what they're building!
This one looks like an easy fix anyway, what I would do is get a long, flat piece of metal (3/4mm thick, 5/6cm wide, 1mt long) and bevel one of the ends at 45deg. or more so you get a nice sharp cutting edge. Then insert it into the cable channel and press the sharp edge against one of the screws right where they come out of the wood, and hit the other end of the metal bar with a big hammer a few times. I think that should cut those screws easily (or at least bend them so they're out of the way).
Good luck!
