I spoke today with Tmobile and was told that if you have Netflix it will block future purchases on the play store. However, if you then go in and make one purchase on your credit card, or other PMT option, it will unlock the block and the next purchase should be available to go thru to your Tmobile bill.
Uh I think the rep explained it wrong or you understood it wrong.
Netflix on Us turns off CARRIER billing
You can still make purchases using ANY other method as you see fit.
Im so glad that I dont have to deal with that.