Have had a large double glazed Glazing Vision rooflight installed for approx 6 years when the double glazing started to fail. I located the original invoice with al the terms and conditions of which there are many. Of course the unit was only under warranty for one year. I phoned the office and spoke to "customer service " who basically said the units were not built to last long term and I would have to buy another one. As the unit originally cost in excess of £6k there is no way I would buy from this firm again and will certainly be checking the warranty conditions on the replacement.