Tiffany&co. Necklace; Help(:?

I bought a necklace from www.tiffanys.com I wore it for over a year when I noticed it was turning a bronze color. I took it to a local jewelry store and asked for it too be cleaned. A few days later the man at the jewelry store called me and said it was not good quality silver and that he had noticed many tiffany items like mine. If I take it to the nearest Tiffany store do you think they will replace it???