Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
Was your phone sold on eBay.com or some reputable major website?
Unfortunately, everything about this points to your having been sold a stolen phone.
The honest thing to do: take it to the police, report it and its serial number and model #, and perhaps give it to them too. And describe the fence who sold it. This is the most honest thing to do with a stolen phone... though I'm sorry it will be a loss for the amount the fence charged you.
There is no way to unlock an iCloud locked phone. It is an anti-theft mechanism that is supposed to be unbreakable, and is usually activated when the phone is stolen by the owner.
I'm sorry but there is no better conclusion possible for a case like this. I sympathize, but you have been taken in by a dishonest or criminal seller (known in slang English as a 'fence'.)
Since this is not an answer that could please you, I do not present it as an answer, but just a suggestion. I have Opted Out of this case also. This opens the case to others, in case another bit of advice is possible in this sort of case.
That's puzzling. But evidently stolen property should be turned in, I think.
I have passed a request for a refund to Customer Support at JustAnswer.com, which will take care of it with reasonable promptness. Thank you for asking your question here at JustAnswer.com.