I bought a used iPhone 4 from a mobile shop in Abu Dhabi, UAE. It was in good condition but there was a Find my iPhone lock. I thought this is a normal thing, and can bypass it if I restore the phone - that's why I bought it.
I used the iPhone for one week, then tried to restore it with iOS 7.0.3 but after the restore, the activation screen showed "This iPhone is locked with an apple id s.....@gmail.com". Then I tried my Apple Id instead, but was unable to use another id.
I went back to the mobile shop for help. He tried for one day but with no success. He said he bought it from Dubai from a person he doesn't have contact address or number.
How do I get the iPhone unlocked and can use my Apple Id with it?