My mother-in-law just noticed she was almost 2GB over her 1 GB plan. She's been known to turn mobile data on and also disable the limit data usage setting on her phone (she has Wi-Fi), so we thought that was the issue again. It was, but I also noticed the Amazon app on her phone was by far the most outrageous data user, accounting for most of the mobile data use. Obviously nowhere near the $9,000 in the above article, but looks like Amazon has a potential problem on their hands.
I manually force closed and disabled her Amazon app, so at least it shouldn't be accessing the net at all anymore.