I quote from a source:
After SingTel's latest move, M1 responded yesterday by lowering its cap to $30, and raising its amount of free data to 12GB too.
It said that it introduced the new cap so that 'customers can have peace of mind when they are surfing and won't suffer from billing shocks'.
I think it would be a giga-shock to me if I ever hit 12GB.
iPhone battery performance and cellular internet speed are incapable of making its user hitting 12GB.