Default Phone relocked to Tesco

Hi Guys,
I have a problem with my Moto G 8gb that was originally on Tesco mobile. I unlocked the phone using an ebay code when I received it and have been using it as a backup with my Vodafone sim, however I recently put my Orange work sim into it and the phone appears to have been relocked to the Tesco network. My Voda sim no longer works and neither do my GG or Orange sims, the only one that works is the original Tesco sim. The problem is, the phone is not prompting me for the network unlock code when rebooted.

Previously I was running C-Rom but have reverted to stock (4.3 from original backup) to no avail. Any help would be gratefully appreciated since I can't find a valid reason as to why it won't prompt me to enter the network code again.

Thanks

Si