It shows statistics of your calls/sms/txt/data traffic and lets you set limits for each of these plans.
Call Meter supports a huge amount of billing modes to let you adapt it's behaviour to your operators billing.
This app is open source software build in spare time. Adding bad comments in market won't help much to make it better.
Please add your issues with this app on the app's website.
There is a complete rebuild Call Meter 3G available in Play Store. It has a huge amount of new features like widgets and alerts.
It's new architecure allows more complex plans.
Feel free to test it and help me make it more userfriendly as it is currently. ;)
Feel free to help translating this app to your language here: http://ub0r.de/translate/cm2/