Just done a full upvc clean, windows inside and out on a friends house, they have just had an extention built with new concertina doors. They have had no end of trouble with the builders but they have finished and they asked me to come and do a full clean. Done the outside of the house and then started the inside which had bits of plaster on the windows, I used a spray bottle with pure water and a couple of cloths, all was good untill I started doing the new glass, when you look close at it it has loads and I mean loads of tiny imperfections in it. Any I cleaned the concertina door then moved on to another window, as I looked back at the door the sun was streaming through and I could see four or five scratches at the top, I never used a scraper on them and never heard any scratching when I was cleaning it. I asked the lady if she had noticed this before but she said no, but it was so dirty she would not have seen it. She told me not to worry but I am!!! What sort of cost would it be to be repaired ? I've looked on youtube at the toothpaste thing and had a go but it made no differance.