WENT TO THE APPLE STORE TO PORT OVER, AND T MOBILE IS NOT OFFERING A MONTHLY PAYMENT PLAN WTF, WHAT IS THIS?

Me and my gf showed up to the Apple Store early and stood there for a hour with a rep trying to figure out why T-Mobile is not offering any payment plans for financing & porting over from METRO service. LIKE WTF. The rep said it could be some kind of fraud protection but even she was super confused. wtf is this T-Mobile? How can I get the monthly payment discount for porting over & financing a new iPhone. Why is it not giving us an option to do that.