I have recently had double glazing fitted and on closer inspection of the glass have found there to be dirty marks on the inside of the glass. The installer is claiming this to be normal and at the moment is proving reluctant to change any of the units. Having spoken to one of your colleagues she said that you may have a list of people who could come and give an independant opinion of the problem. Could you forward me any details you may have. I am based in Orpinton Kent BR6 7NS. I look forward ot hearing from you. Kind regards Andrew Dugard