How to disconnect the iPhone I bought in eBay?

So do you guys thing that there's way that I can cancel his account or do some thing. It is a sprint iphone 4 and I have sprint account so I need put the iphone on my account but every time I call sprint they are telling me that he needs to cancel his account. So help. Oh! And I bought two iPhone from him. So help me. And I keep massaging him trow eBay but he doesn't respond

Added (1). And his phone is disconnected because he didn't pay his bill but I still can't swipe the phone my account and I don't want return the phone to him because someone told me if I return the phones he would not give me the refund and ebay would suspend him and that's it. And after that he can make another account and I won't get my money back. And I asked eBay for his number the number they give to me was the number that Is active on the phone he sold to me so I can't reach him.

Spring can think that You stole the phone from him and they have to verify it. They has to call that man and ask for it, You could also send them a message and tell them that You buyed the phone and You have the proof(from Ebay), or make a screenshot and send it to them.

Return it

You need to call eBay and have them contact him for you. If they can't get to him, you can return the phone and eBay should refund your money back to you.