Power supply

Hi All, sorry if I sound stupid but bought an xbox one off ebay and it arrived today. Seller said it was complete with all cables but it is missing the power cable that plugs into the power brick. I've looked online for spares but they all appear to be a different connector with 3 pins but this one only has 2. So 3 questions: 1. Have I got a strange model of xbox that requires a different power supply, 2. If I bought a completely new power brick and cable with 3 pins would it work, 3. If I were just to replace the cable what one would I need where can I find them.
Thanks