Sorry, but none of us nor Apple can help you in this situation. You likely have purchased a stolen iPhone and have been scammed. Only Apple can unlock it, but they require the original proof of purchase receipt or the original owner's Apple Account credentials. You need to get a refund for the iPhone as it will forever be unusable to you.
Next time, purchase from an Apple Store or Apple Authorized Resellers where there will be no Activation Lock present. Also read the article Mac Jim ID provided that lobsterghost1 wrote about before you buy a used Apple products and the risks involved.