iPhone 4 Unlock not Recognized by iTunes

Hi there,

For Christmas I received a locked iPhone 4 that was purchased from Kijiji. The phone was locked to Fido (an off shoot from Rogers) . I paid Fido $50 to unlock the phone for me, so that I could use it with my Bell sim card. After they unlocked it I tried connecting it to iTunes and inserted my Bell Sim. The phone still says "No Service" and iTune prompts me by saying that the Sim is not compatible and that I need to unlock the phone to use it. I've contacted both Bell and Fido and they say that the phone looks to be unlocked. I've also looked up my imei number on IMEI.info and it says that it's unlocked and needs to be connected to iTunes. Bell told me that I need to get an LTE sim card for it to work, but I just bought a new Sim and from what I can tell LTE sims are only required for iPhone 5s.
Any help would be really appreciated, I've already lost quite a bit of money on this and I just want a working phone. I don't know if they will help me at the Apple store since it's not their phone and it's warranty is expired.