Taxes on data add-ons

I don't understood why I am charged 17% in taxes on data only add-ons when i have exceeded my data for the month when i have already paid the taxes on the unlimited voice and text messaging. I work in telecom and as far as I know, internet access is non-taxable. It isn't even assessed state sales tax. Yet for some reason i am billed $1.70 on a $10 data add-on in a state where sales tax is 7%, (which as i stated earlier, internet access is non-taxable) none of the other fees such as FCC regulatory fees, Federal and State USF, e911, etc apply to anything but voice service which I have already paid on my monthly regular unlimited voice and text package. 

Assuming AT&T has 10 million prepaid customers paying as I have, an average of $10 a month in taxes on data only add-ons packages, AT&T would be collecting roughly 100 million dollars per month in fees that they are collecting illegally. Is this not grounds for a class action lawsuit? 

[Per Guidelines: Keep it Relevant and Appropriate]