I don't own an iPhone.
I've been paying AT&T oodles for years and have reported more than once that their service is spotty in my own home. But it seems that AT&T only cares about iPhone users. They recently released an app so that iPhone users can tell them where their service is weak. Of course, the puzzle is how to actually use their network to report network problems when that same network is not working.
And if your plain old cell phone doesn't work? Well, you can wait on hold with customer service on your land line. Then complain. And then they will likely never get back to you or fix it. That's what happened here.