Is paket internet indosat im3 trolling me?

On June 23rd, 2012 i started to subscribe to my current mobile internet data plan on indosat im3.
I took a 500Mb data plan for 25K Rp per month.

It was fine at the beginning although the connection is not that stable enough, sometime frustrates me actually.
But then i noticed something very funny.

I use Samsung galaxy nexus with android ICS.
It has this nice built in feature in the settings area called mobile data usage.
The thing is that according to the data usage report i got there, I've only used about 177Mb until this blog post written and posted.
And yet whenever i check my data usage plan officially via SMS to 363 (indosat), it says that there's 0Mb left.

So, where has the approximately my 300Mb left?
Then again, i can still connect to the internet without being extra charged by im3.
I've checked my balance and it's still untouched.

Who's been trolling me?

Tomorrow on 23rd july, my plan will be automatically extended. and it would cut another 25K from my balance.
Let's see what will happen.