I also hit the same situation. Sunday night i checked mine usage received less than 1MB sent also less than 2MB. I only turn on the 3G and data when I used. However yesterday night, without uploading anything just go through the eBuddy n FB for less than 20 minutes. Suddenly it jump to 4gb for both send and received. Shocked !!!!
I called Maxis center, the operator said cannot check the usage only can check whether my unbilled amount is RM250+ as 8GB already exceed my 1GB plan.
How come Digi can check Maxis cannot check? very disappointed with their service.