[Q] How to unlock rooted i9505 from EE network topic

Hi my contact run to its end and EE has an audacity to ask me for £20 quid to unlock a phone that they locked, that now belongs to me. As I have absolutely no intention to pay for it or upgrade, nor conduct any further business I would like to remove the lock, I am on new cyanogenmod 12 and rooted with CWM recovery. It shouldn't be that difficult, anyone is willing to help?

Thanks!:D