Incorrect Billing from ATT. Says something in charges, charges something much more at end

In https://www.att.com/my/#/changemyplan My Bill says:

Current plan

xGB
$xx.xx/mo. per month for x devices

My monthly bill is 30% more than what my plan says. I have international calling blocked, I have no devices I bought through ATT either under contract or as EMI so nothing should come up there. I have no other additional fancies. I speak to customer care and they promise some amendments. Next month I get the bill and nothing they promised appears on my bill. Its frustrating working with ATT. Either technology and customer care don't work hand-in-hand or they think customers don't see bill and just auto-pay. Is their an email or an authority beyond customer support to whom I can talk and explain that their billing is incorrect.. Because when I talk to their customer care, they look at current bill as encyclopedia and disregard any benefits prior customer care rep gave