Samsung India — Mobile technical issue

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Mumbai City, Maharashtra, 400704

As I purchase this product though flipcard on Oct 2015. I have been given defective peice. Mobile automatically switch off and switch on while having call to any no. The battery backup is so low..during call u an not able to hear voice form second person.phone not responsonding good while acess net.. So many other issue see there with my phone .pls contact me..[protected]