I got a samsung galaxy s4 from koodo on contract. Currently with my monthly plan, I am using the tab medium to pay for my phone. I left canada for a couple of months, unlocked the phone with koodo to use outside for other network providers. However now the phone is unable to detect any mobile network. I haven't returned to canada yet, but I inserted multiple sim cards and the phone barely detects the mobile network. So I cannot make or receive calls and text messages. What should I do? Any useful advice would be much appreciated!