first off i would suggest to check online as how much data has been used. On top give it 24 hours to reflect the data usage on account as it is not updated right away. Last solution i would say is give a message to the mods and ask them about a solution.
seems fishy, did u look at ur history? look and record ur history and then contact the mods, demand compensation if they are shorting u.
@slash407 999 times out of 1000*, when someone on the community posts about incorrect data usage amounts, it turns out to be something other than PM's usage tracking being incorrect.
*not a actual statistic; my semi-educated guess based on 3.5 years of experience in the community
@mccutcha I see you've selected the message I quoted above as the solution. Have you done the other troubleshooting steps that others have mentioned so far in the thread? Have you verified what if anything shows in my add-ons and data on the Overview page in your self-serve account? Have you verified your phone's data usage limit settings? To me, these are much simpler than spending the time to add up all the data events in your usage history and "demanding compensation" as suggested.