Sprint note 3 wont release carrier after unlocking ? please help

[Cxbxr_3]

We have paid off the phone with sprint and trying to go to tmobile we have a tmobile sim card in it now but says invalid sim' the tmobile tech called sprint & supposedly unlocked the phone now a day later sprint has cut off service & the tmobile sim isnt working what can i do ?

 

[rgd1101]

contact tmoblile, your current mobile service provider.