i purchased 30 pcs of 500 GB hdd (ST3500320AS) in february 2009 from radington india limited, kolkata branch.all of them are oem drive.still today no problem occur on replacement.
i think you purchased a paralal imported hard drive.
if you want reliability and price is not a matter, then go for any enterprise storage. your first choice should be seagate baracuda es/es2.0 drives. they carries 5 years warranty from seagate. fortune imports them in india.
or you can go for western digital re3/re4 drives.