I think it pays to read the fine print! Probably you didn’t get the phone because you get great rates on yoiur daughter’s plan. It’s like the story of the razors and the blades (in the olden days). They gave away the razors because they knew you would keep buying the expensive blades from them!
Good on you for walking out!! This is not strictly a financial question, but I’m posting it because your experience may help others!