Making Online Sales over a lie

Last year I app**** for an iPhone deal ,which I was told I don't qualify for but I can take a sim deal then at exactly 6 months I'll be able to take whatever iPhone or device deal that I want .I therefore did that then 7months later I called them for an upgrade then I was told again that I do not qualify....I then reminded them what they sold to me but they still refused to give me the deal that they promised me ....I therefore asked them to cancel their contract since I don't need it anymore but they did not ....now I keep on receiving receipts that I'm owing them hence I did tell them that I no longer need their services because they did not keep their promise to begin with