I don't know what you paid so I don't know how much trouble to want to go throught to fix. But if it is aluminum "Hard Anodizing" may be a fix for you. Just look up metal plating or finishing in the phone book and you can find a local shop to see what they have to say. If all the white is just salt residue and it is just the lock that is corroding you may just need a good Stainless steel lock to replace that one. ??? good luck.
www.h2ohummers.com