Yeah, you play a dangerous game if you are a power retailer selling at fixed prices to consumers, without having extensive hedging agreements in place.
Octapus might be big enough to carry the risk, but for most of the small power retailers, there is the potential to loose a company bankrupting amount of money in a few days in the event of some abnormal network conditions.
I worked for a power company a long time ago. Couldn't get the terms we wanted in a hedging deal, so we actually built a little diesel peaker plant to manage the risk of very high wholesale prices.