He has a small bedsit studio flat at Dora Creek which he rents out to single people or couples and, predictably, the power bills have to date been modest enough.

"I've been told by tenants that their bills are normally around the $300 mark at this time of the year," Mr Shamley said this week.

Then a pair of young friends moved in only to be shocked by their first quarterly bill. It was for a staggering $3401.

"According to the bill, they had used 9863 kWh of power in three months which is basically impossible for two young people that are out at work all day," Mr Shamley said.

"They had no heavy draw equipment or appliances out of the ordinary and what they did have was used less often than most domestic households."

Mr Shamley subsequently organised for a specialist electrician to thoroughly check the building's electrical system.

"There was nothing that could account for the sudden huge increase. The theory is that the probability indicates a decimal point has shifted on entry into the system or in the software," Mr Shamley said.

A spokesperson for the privatised electricity retailer Energy Australia said the ombudsman had now become involved.

"The ombudsman is looking into this matter and we will continue co-operating with the investigation," the spokesperson said.