Feeling very mislead by ATT store manager ( BOGO )

A few months ago I went into the ATT store, to see about the BOGO deal as my 5s was dying. The manager explained that the BOGO would only cover $750 towards the purchase of the new iPhone X ( One @ $999 and one @ $249 ) and asked if I would like to buy the second ( $249) outright, which I declined. He explained that I would be billed the full amount , but would receive a $25 a month discount to cover the difference. I asked if I could pay the phones off early, which he repeatedly said yes. By agreeing to this, I am forced to pay $75 a month, for 30 months, or pay FULL PRICE for both phones... This completely negates the NEXT plan which according to my account I am on, as I cannot pay off my phones to allow me to purchase the newer phone if I choose to. I will probably be paying the full price for my phones, cancelling my service, then taking them to a different carrier... I feel as though I was lied to, and will be sure to let everyone I know to be aware of the way ATT is doing business....