Q: Activation Lock. Purchase Validation

Hello

Case 598547081

I have a problem with activation my iPhone 4s. I have bought the iPhone in

a shop one week ago and update iOS 7 yesterday. After update iPhone has an

activation screen and asks previous owner's Apple ID and Password. I don't

know Apple ID and Password; I haven't communication with him. I can not use

my iPhone 2 days. I am so disappointed this situation. Can you help me to

disable this function, please?