I bought a iPhone 7plus off Shpock, the guy seemed really genuine and said that it was unlocked. When I got home i put in an O2 sim and EE sim, I got the message that that the Sim was not recognised. I had the IMEI number checked and it's locked to Three, I ordered a Three sim and it works. So I've spoken to Three and they say they don't network locked their phones, but yet this phone is locked to Three. How is this possible?