Automatically Restarting Brand new Note 3 Neo Mobile in just 3 Days

Hello..
I bought Note 3 Neo on 4.11.2014. After bought Brand new Device Note 3 Neo just after
1) i facing problem Mobile restarts in Camera Mode.2)
This was primary Symtom then it becomes very slow & Hangs 5-6 times in Days.3) when i connet 3G Network it never shows signal too… so i contact Samsung service centre,they upgrade software But still Problem not solved.
Please Help….i am very frustated from Samsung for buying this product