Unlock network locked device

[Moozer71]

Hello. I have an old device (Galaxy J3 (2016)) but it is network locked to O2. I was hoping I could use it for my daughter whilst her phone is getting fixed, but she is with another network provider. Is there any chance you could help getting it unlocked so she can use her SIM? I've tried live chat on http://O2.com but it won't let me speak to an actual person. We don't have the device linked to an O2 account. Thank you.

[Cleoriff]

@Moozer71 

This is a guide to unlocking an O2 device Guide: Unlocking an O2 phone to use a different SIM card 

It may not work for you so  you would probably be better getting it unlocked at a mobile phone shop or market stall.

[Enlli]

It will need to be running on O2 for a few days so as to be seen on they system.

Easier to use a mobile phone repair shop