Like most if not all data plans, they are under fair usage which means there will not be additional charges. The speed is throttled, that's all. By the way, it is now known as Talk and Surf1. Cheers.

For those of you who are still not wise to Maxis' unfair unilateral revamp of this particular plan, I just found out that the call rate per block of 30 seconds had in fact been increased from 12 to 15 sen per minute and the charge per SMS was also revised upwards.

For information, I have migrated to other plans and other telcos.