sounds like a fairly standard problem for a shootbolt locking system. one part fails while the rest tries to work. Your three options are:
1) disable the part which is not working leaving you with (normally) 2 parts of 3 working.
2) add a surface lock on the side where the part has broken...
i would get a small claims court form and fill it in, send a copy to hi stating he has to be in touch immediately and has 7 days to finish everything, then file this with the small claims court.
I would probably feel by this point that he will not be back and if you have no glass start...
The thing you need to be aware of with energy rating windows is there are still a few problems with some extrusions making A rated. to get to the rating it has meant removing some reinforcing making the windows more liable to movement or warping. 'B' and 'C' still have to meet good levels so...
Add ons are usually required where the plaster protrudes so far that it would interfere with the opening of a sash or door frame, if this is not the case they have probably been used (as said before) because the frames were not measured correctly. You do not normally need add ons to allow...