Is it peeling or is there something white on it? Sorry, I don't know the difference. But, if it is something like paint on it, I would try a magic eraser. But, let someone more experienced reply and offer suggestions.
That's discouraging... I had a mark similar to yours on one of my bags and it looked and felt like the finish was missing, but when I wiped it with a baby wipe (eh, let's be honest, it was more like scrubbing...), it turned out to be a superficial mark and came right off. If you decide to use a magic eraser, be careful - it's basically really fine sandpaper.