Please help me with this?

OK so yesterday I took all my saving to buy my dad an iPhone for my parents twentieth anniversary and I bought it off craigslist and its not reported stolen or anything but the phone is still on its still activated with Verizon and I contacted the seller and he won't turn the phone of therefore I cannot turn it on on my account so is there anything I can do to get it turned off or something I was going to sell it to someone who fixes phone but now I can't because nobody will buy it from me for more than 70 dollars and I spent 150 and I really need the money back or the phone on.