that would drive me insane too!
presumably there was some sort of agreement / contract signed before the work started? if so, does it reference the cad drawings you were given?
was any of the payment made either by credit card, or as part of a credit agreement? if so, it might be worth speaking to the credit provider as they are likely to be fairly helpful (there's a weird bit of law that makes it their problem too) so might be worth speaking to them
i'd still say that they clearly haven't supplied what you were expecting them to
was it by any chance a nationwide company whose name might sound a bit like "angular"?
i can see what's happened. they have put the ridge in the centre of the area that the roof covers, and the fact that there is only an overhang on one side means that if they have the glass all the same width, the centre won't be in the centre.
i can't see any reason why you couldn't have it central, other than the geometry might prove a bit of a pain to work out. but then you'd think that was done on computer these days. i'm not a window installer though