Thanks for your input.
Oh, what I meant is that whether the free 30GB offered by shop retailers can be rolled over.
I have asked one of those mobile shops, they mentioned if I subscribed through them, I will get an extra free 30GB.
Example if I opt for the 10GB plan I will eventually get 40GB in total, however roll over will still be based on the 10GB instead as claimed by the shop assistant.
Hence I am seeking for confirmation whether this is true, especially to those who have already subscribed through shop retailers and also received the free data.
In short, would like to know whether the roll over is based on 10GB only or 10+30GB?