using reward points to purchase a new device

I have been a customer for 7 years my plan is a business account with five lines. Over the course of 7 years I have accumulated a significant amount of reward points. I have never used my points, but now I am interested in using them to purchase a new device through the T-Mobile store. My question is how do I go about accessing my points and then using them on a device which I choose to purchase. Everything that I've looked through and researched on the T-Mobile app and on their website only says something about Tuesday and nothing about reward points