One of my customers has had a huge glass balcony built on her rooftop (30k of glass!) and they have some marks on them, which were caused by the window fitters suction cups, and I've tried all sorts to get them off but they still show up??
Any ideas what I can use to get rid of them? They only show up when they are wet or in the morning dew.
This is one of my top jobs and Ive said I will ask some experts that I know

Cheers Dave