I think something like:
3G Watchdog Pro SMS extension (I cannot post the link, it's in the play store)
although I haven't used that app, as it requires the paid version of 3G Watchdog Pro. I'm not against paying for the app, but I thought I would look for free alternatives first, and I'm not entirely sure it will do what I want.
Certain MVNOs don't provide an online resource for checking data usage. I know that this is part of the cost with using an MVNO versus a top carrier. Being being able to see a report of data usage for accounts, even if it's just a daily report, can help to monitor data usage and activity. It would be easier if I could have all of this information reported to me daily, rather than having to physically review the data usage on each phone.
I'm just wondering if there are any such apps available or if the referenced 3G Watchdog SMS Extension is the only one. And I don't even know what all it reports.