The economics of electricity infrastructure are similar to those of telecoms infrastructure in some ways. However, there are some important differences, as has been learnt in various countries around the world. Hence, although there may well be an argument for some form of competition in the sector, it's not clear that this could work in practice. Artificial mechanisms have been created in some markets to give consumers a choice of providers, but few have fundamentally changed the price of electricity (except for the well-known example of California some years ago, where the whole scheme collapsed, along with the electicity grid itself -
http://en.wikipedia.org/wiki/California_electricity_crisis).
Eskom's previous prices, which were the lowest in the world, were the result of very low input costs and an efficient generation and transmission model - a single, co-ordinated infrastructure, with no duplication, and with local distribution largely handled by local municipalities. The low input costs were partly fortuitous - large amounts of relatively cheap coal, with the power stations built on top of the coal mines. More or less any other generation approach is more costly, despite what you may have heard.
At those prices, there was simply no incentive for anyone else to build electricity infrastructure - even though the official policy was to encourage independent power producers, and to create some form of competitive market. Ironically, it is only now that Eskom is raising its tariffs to fund the massive new investment that is required to keep pace with the growth of the economy that it is becoming viable to build competitive infrastructure. However, anyone doing so would be at a significant disadvantage to Eskom, which has massive economies of scale.
Unlike telecoms, competitive producers of electricity cannot really compete on products (electricity is electricity, after all), or even on customer service (despite Eskom's contact centre). There's also very little scope for innovation and growth of new markets (compared, for example, to mobile phones, broadband, or triple play in the telecoms sector). What is left if pure price competition - a bit like submarine cables delivering bandwidth - and hence the economics above apply.
On the whole, the only thing that is wrong with this tariff increase is timing. It should have happened a long time ago (or been done more slowly, over a period), and we wouldn't be where we are now.
Fit a solar geyser, and use high efficiency lights, and you'll probably be able to keep your account where it was, and you'll be saving the planet.