Nature of brushed titanium, I'm afraid. It's why I always get the buffer out and polish my bike frames to a mirror shine when they come from the factory brushed. A few rides and they look just like your bracelet. Manufacturer recommeds a red Scotch-brite pad to reapply the finish - it's what they use in the factory'. I'd DIY rather than pay £300, especially since in a few weeks you'll just be back at this point again.