Perspex can be cleaned by washing with a solution of luke warm water with a drop of washing-up liquid, using a soft cloth to loosen any dirt and grime. Then, rinse with cold water and dry with a very soft cloth to prevent water spotting. You should not use chemicals, glass spray, or other abrasive cleaning materials, nor should you use any form of scraper or squeegee or other sharp instruments. However, like the posters above, I would take it up with your supplier. Good luck!