Sim Unlock Help pop up to unlock doesn't appear topic

I have a Rogers Z3 (bought outright) which is bent so Rogers sent me a replacement. Instead of the usual Rogers logo on startup the phone has an number 3 and a colourful FIsh (http://www.three.co.uk) and when I insert my sim the phone does not recognize it. I called Rogers and they sent a replacement. Well the same thing is happening. The customer service rep couldn't explain why but thought it may be a phone from another provider gave me an unlock code for the phone. The problem is when I insert the rogers sim or a bell Canada sim I do not receive the pop up box that prompts me to unlock :confused:. Can anyone offer any suggestions? Thank you