@ctzalifah,
I used a non-JB set.  Initially, I just put in some crap stuff in the APN.  When Maxis was officially announced as the official provider here in Malaysia, I ter-updated my network settings and my APN settings "disappeared"; I then created a fake profile.  It worked for me and a couple of my friends; have no idea why it's not working for U though *shrugs*

@tnsai,
You could always check with Maxis if they'll allow you to upgrade but from iValue 1 to iData they might not entertain U.  If it's iValue 1 to iValue 3 maybe got chance   Anyhow, no harm checking with Maxis.  Also, don't forget to ask for waiver of whatever fees needed to be paid.

@developer,
I've been told by those using jailbroken phones that their usage counter ain't too accurate.  It apparently is quite accurate on the non jailbroken phones.