AT&T unlimited data plan is shit.
They started throttling it 2011 if you ran over a relatively low amount of data (like 2 GB per phone).
So you'd be running at max 3G speed.
Called them up and bitched about it, and they told me that they "sent a notice" in 2013 informing me that unlimited now meant unlimited + throttling.
I objected and claimed that was changing the contract, and they told me that their unlimited data plans only existed when 3G was the highest speed available, so all they have to do is give 3G to satisfy it.
Dirty.
After like 30 minutes of bitching and debating, the manager I was speaking to finally made a compromise and switched me to a 15 GB plan with rollover for the price of 10 GB with rollover -- something not available at the time to the general public.
Last year they were fined $100 million for this:
http://money.cnn.com/2015/06/17/tech...ited-dat-plan/
... but it's unclear if they actually changed their policy.
And of course, the customers got none of that $100 million.