Glazing packers may well have caused this, but all the ones I have ever come across are as wide as the thickness of the whole double glazed pane. Maybe the installers have used something else.
I too was mugged by the promise of 10 year double glazing warranty on my conservatory. I have numerous units that have blown and have let in moisture. I might just knock the conservatory down and build a proper brick and tiled roof extension as it is over 10 years old now. Probably not much more expensive in materials than replacing my 25 toughened units. Some have Georgian bar inserts and there is also the risk of the hassle that some won’t fit.
I have wondered how feasible it might be to remove a glazing pane and split the two glass panes. If this can be done, the glass cleaned up with a suitable spirit and a flat blade scraper, then you have at least recovered the glass. A reputable local glazier could then re-assemble them with new spacing beads and the correct gas.
I don’t understand why some units last 20 years in the same position as others that only last 2 or three. I can only assume these cowboy outfits cut corners with the quality of materials and don’t have people properly trained to do the job.
It’s a mad that MP’s haven’t legislated against these companies electing to go bust and immediately restarting under a new name, same building, same staff, when they are clearly not insolvent! These guys are running rings round the system and it is not fair to allow them to rip off trusting punters and leave them with all this hassle and expense. It also tars the rest of the industry with the same brush.