A quick question - was the balcony glass for the building contracted directly with a manufacturer, or through a local supplier / dealer / distributor?
My understandig would be that If the purchase agreement was directly with the original manufacturer, yes - then they would be the ones who would have to stand behind their product. If the purchase was through a dealer / distributor who held the contractual relationship with the builder, then they would be the ones who would have to stand behind the product, and they would have to be the ones who would have to have the recourse to the manufacturer they were representing - unless there was a specific manufacturer's warranty on the product that was passed through to the developer as part of the contractual terms for the purchase.