Last month, I got an AT&T hotspot and was quite happy with it. I have the 5GB/$50/month thing. My house is among the many places where there is very limited Internet options. The AT&T signal is good there and most of them time I get good speed with it. In all of January, I used about 2.5GB of data. Quite good since it even included streaming a single TV program.
A few days ago, I suddenly started getting emails from AT&T that I had used 3.5GB, shortly after that, 5GB and they added a gig for +$10. I shut off my hotspot (airplane mode) at the 5.99GB mark. I had a few web pages open but no streaming and I have ad blockers to cut that kind of data usage. My firewalls and virus scanners were up and I ran them afterwards to check my system and it was clean. It had run thru 5.5GB of data inside of 2 hours and I was not doing anything that should have eaten that kind of data. Yikes!
I called AT&T Tech support and all I got was that they registered a sudden increase in data download and too bad for me. They insisted it could not be their meters going haywire (I believe Technomadia had an episode of this with their Millicom hotspot). The only suggestion is that I turn the hotspot off when I'm not using data - something I already do. It is clear that AT&T will do nothing about it in true Telco fashion - their motto is it is always the consumer's fault. And they really don't care. They have zero incentive to fix such problems. To them, they just charged me an extra $10 and didn't have to provide anything for it.
What I suspect happened is that the big ice storm did something to their network and in the repairs, someone did something that triggered a false data download and I am screwed. There is just no way I could have legitimately downloaded 5.5GB of data inside of 2 hours. Even streaming wouldn't chew up that much data so fast and I don't stream.
I worked for years in computer systems and I know how easy it is to make an error and screw up networks. Especially when the shit is hitting the fan and you are scrambling to get things working again - exactly the situation after the ice storm. Most of the weekend was dropped down to the HSPA+ network on my phone so it is clear they were having problems.
So the bottom line is, LTE is great but watch out. Caveat emptor, indeed.