I've always been really careful with the back window as I read a long time ago someone on here having an issue with the black part of the window (turns out it's sprayed on) so when scraping ice and things I'm always ultra careful so I'm completely lost for words at how this has happened. Especially since it seems to have happened whilst being washed with a sponge!
Thanks for all of your replies. Looks like I'm going to have to go to my dealers.
