hi
seems to me like there fobbing you of...when you look it up in a dictionary such as
http://www.thefreedictionary.com/corrosion
at cleary says corrosion is
The breaking down or destruction of a material, especially a metal, through chemical reactions. The most common form of corrosion is rusting, which occurs when iron combines with oxygen and water.corrosion and rust in the same sentence..try fighting it mate