Offer of 74% discount not respected. Cox internet preferred 100

Could you please explain me,  why if I sign and register my order with this offer that I find in Cox.com now you don't want respect and complete it? Thanks that I have those screenshot and I even read the desglose when you explain moth by month how much I gonna pay and the price was 31.98 until month 13 that back to regular price. I talk to some one on Cox by phone and nobody know nothing now.