How to get a cell phone unlocked

What does it take to get a cell phone unlocked? I was on an xfinity mobile plan and canceled service. The phone was paid off well over 48 hours ago, no outstanding bills, we've had service within 60 days. Called 3 times to have the phone unlocked each time they told me it would be unlocked in 24 hours and an email would be sent for the code. No such email, and was never provided any follow up information or ticket for this. I either want my money back for the phone or to have it unlocked, I'm pretty sure xfinity is legally obligated to unlock the phone at this point. How do you get them to actually unlock the phone?