I have a iPhone 14 pro trade in promotion i got for upgrading my plan. I believe I'm getting 800 in credit so monthly I pay 8 bucks for it.
I wondered if (even though the promo is for 24 months ) I can put more money on it from time to time to eventually finish paying it off/lower the balance instead of only paying 8 dollars monthly, so I can change my plan to a cheaper plan, since I got the promo for upgrading to the new premium plan go2plus or whatever it's called.
I've been told paying anything extra on a promo phone would cause tmobile to charge me the full balance the next bill after. Please help.