Starting with a lie

So, I just signed up for T-mobile after years with Xfinity because of the promise of "4 i phones on us" and a monthly bill at a flat rate of $200. My first bill is $265.00. When I called customer service about the discrepancy they offered no amelioration to the obvious overcharge compared to what I was promised. Simply repeating that 4 lines on us was a lie...only two lines are on them. So basically too bad, we lied and you're stuck paying more than agreed upon. Not a great way to start a business relationship. Anyone have any idea how to correct this other than taking my business elsewhere?