Moved from Verizon to T-Mobile. How do I get T-Mobile OS on S4 Mini?

[Johnny27]

I moved to T-Mobile from Verizon this week. My Galaxy S4 Mini has Verizon software and connecting to the Play Store and other sites won't work as Verizon thinks it has the phone and T-Mobile doesn't override for some reason.

Any ideas to fix this appreciated. (The T-Mobile store was not able to provide any help on this for some reason.)