Give them a call, I've just did. My wife's number is under my name, currently under smartplan 98. I've read somewhere that they've upgraded the smartplan 98 to 10GB with 4GB rolling, 300call minutes/sms. So, I called them this morning, at first the rep hesitate, saying I should complete the contract (Oct 17), then I used this "Are you becoming like MAXIS now?", the rep was giggling and then said let him check for a minute or two, put me on hold and then said, yes, we could actually upgrade the data and calls/sms to the latest as long as you're paying the same/more without a need to breach the contract. A minute after that got the confirmation sms. All is well! ..

Now, I should've asked the same question for my other account, my kid using it for her iphone.