Just to update, got a call from DiGi, they've made some changes from their side and it seem like the charges is stop now. DiGi promise the previous charges will revert back to me once the bill comes out.

Confirmed again, APN must put in blackberry.net, put in anything else or leave it blank will get charge PAYU.

If its change to GPRS, no i won't charge you PAYU.

You will only get charge if APN settings incorrect or use it as IP modem. Else GPRS, EDGE or 3G all works fine and no PAYU.