I think people are mistaking the iPhone data usage as actual monthly usage, especially that 60gb usage guy. The usage you find in cellular settings is amount of usage used since last reset, not your monthly usage. You have to text or log in to your carrier to see your monthly.
On my phone it says 38.2gb, but my current month is only 2.5gb, and monthly average is 9.7gb.
In that case, I just logged into my T-Mobile account and since January 21st - Current I've used 8.95GB
However I think it'd realistically be higher since I stream on rhapsody often which doesn't count against my data / get noted......I think.