Crumbs what a great bunch you all are, thanks for the reply's . My full intention is not to admit to anything, but to prove to them that the equipment that we use is to the highest standard. Yes at time we did use a scraper but only in small places, not the whole window. We firstly sprayed a concrete softener then washed the window, and then if there was anything left used a scraper to remove. through research I am totally convinced that the fault lies with the window itself, or the messy plasterers. I am getting legal advice Mon morning as part of the insurance, So if you don't mind I will keep you informed . Again, a massive thank you for your responses. my best regards,Mike