Charged for overage data??

It sounds like you are on Mobile Share plan, $50 for 5 gigs of data and $25 discounted line fee on each.  If you exceed your data allowance you will get charged for the extra gig of data.

You could switch to the new plan and have no overage charges.  Same total price, but different configuration of price.

Line fees are a flat $20 each.  Data is $60 for a 6 gig plan.  Total before tax is still $100. 

https://www.att.com/shop/wireless/data-plans.html

If you are comparing to Verizon, you would pay more with more data, or $10 less for less data.

T-mobile and Sprint do not have the same coverage and must compete the only way they can, with price.  Neither are significantly less expensive than Verizon and ATT. 

---

@Ninaangel14 wrote:

I pay more than $100 a month for 2 lines with 5G data share and now u are trying to collect more money from me when there is other wireless phone company that offer 20G for $100 and 4 lines???? Do you want me to switch ?

How are they trying to collect more money from you?

@Ninaangel14 inform myself better? Arnt you the one who is complaining about overages when you have options that dont have overages? If you are on a plan without enough data that allows overages, that falls soley on you and nobody else if you get charged overages.

Ah, I get it.  Some just want to complain and say, "it's the principal...".  

Despite having been the only people in possession of the phones and in control of the data you used, it somehow is the carriers fault.