Hey guys, long time reader/lurker; first (or second) time poster.
I initially got the same problem with you guys in regards of the Maxis statement mishap. Imagine that they messaged me sating that I owe them RM600 plus!
So I promptly replied to them that I am under the data plan, 3 gig per month to be exact, and I do monitor my data packets, which has not even exceeded 1 gig this month.
At first, the call centre guy tried to give me an excuse that probably I've been using more than monthly plan I've subscribed (Which is BS), and probably I've been using my phone outside Malaysia (another BS)
After I replied that what they suggested was utter crap, than only they said it's probably the system error.
What I got back from Maxis after my nasty feed back was that:
Data plan is capped at RM450. If you exceeded it, they'll automatically cut it off.
But that is what they say, and not what they did. :-P