My zoom ring on my tamron 17-50 F2.8 quit working. It'd go past their stops, and was crunchy sounding. The gears definately broke or something...so I sent it back in for warranty work since it's only 7 months old (6 year warranty) and they claimed "shock damage." However, I never dropped the damn thing. Now they're asking for $300 in repairs. Goddamn. Recommendations on what to do? Can I argue their claim of 'shock' damage? Poor build quality FTL.