Telkom Internet has been the cheapest option for years and years. Work the numbers and you'll see that there are a few stretches where one or two companies were better, but not much.
But as usual, what isn't on Telkom Internet's pamphlets is ignored completely. Telkom Internet offers local only data on several (all?) of it's packages, but this is just ignored, the same way that them giving 4.5 GB on their 3 GB packages was ignored in comparisons 2 or 3 years ago.
It's not like I have nothing to complain about regarding Telkom Internet, but their pricing HAS ALWAYS BEEN competitive, if you want better, don't ask the pricing leader, ask the laggards like IS to catch a wakeup.