It took four months to discover this. That tells me that the power company demanded an audit, rather than Telstra informing them of anything. This inference is also consistent with the other case I linked to previously in which someone got a huge bill from them.

Had Telstra informed the power company (not the thief!) it undoubtedly would have been caught earlier, when a much smaller sum had been stolen. Moreover, given that black hats can clone SIMs and such, one might think that consumers should be able to demand reasonable protection from thievery from their telecom provider.

Please note that although it's possible that they have a rather long billing period (e.g. they only got bills every few months), such notices would only be useful if they could occur within a billing period, so it still would have helped protect the power company from theft of services.

I have no idea how you managed to carefully read any of the comments and still confused the account holder (the power company) with the woman who misused the SIM card, whether you were reading my comments or those of nagrom.