The fraud may impact on the company's mooted $1 billion plus listing on the stock exchange. Australia is midway through converting from the 150-year-old Torrens title paper system of exchanging property, to electronic certificates. Thousands of land titles are now transacted and exchanged on an electronic conveyancing platform operated by PEXA, a private company owned by state governments, the ANZ, CBA, NAB, Westpac, Macquarie Bank, private equity and property developer Paul Little. In another case three weeks ago, more than $1 million was fleeced from an unsuspecting Surrey Hills home owner in Melbourne's east during the settlement period. 'Not responsible'

The vendor still has not got their money back and the crime is under investigation by the CBA's fraud department. The thefts are likely to put a cloud over the electronic exchange of property, which is set to become mandatory in Victoria in October, with NSW to follow suit next July. Conveyancers, who handle the exchange of a property, say the PEXA system does not require additional subscribers using a conveyancer’s account to verify themselves or provide proof of identity. The hackers broke into the conveyancing firms' email accounts, accessed their mail from PEXA and set up new user accounts. They then intercepted emails from PEXA that notify another account had been added, leaving the conveyancers vulnerable to ghost users who can change bank details during the settlement process, enabling them to fleece home owners.

Both PEXA and the CBA told Ms Venn they were not responsible or liable for the loss. “PEXA has robust fraud protections and strict authentication procedures built into its platform," its acting chief executive James Ruddock said. Mr Ruddock said the PEXA platform was not hacked but practitioners’ email accounts were. A sophisticated fraud was then perpetrated against the practitioners who operate on the PEXA platform, he said. "These are isolated incidents and do not represent a wider or systemic risk to the PEXA platform." PEXA was helping affected home owners, he said.

Dream over Ms Venn, her husband and their two young children are now caught in a nightmare scenario where, because of the theft, they don’t have the money to settle on a dream home they bought near the sea on Melbourne’s Mornington Peninsula. The family packed up and moved out of their Smiths Gully home on Wednesday to a single room in a relative's home while they try to sort out the mess. “We haven’t been able to settle on the property. We stand to lose our deposit of $80,000 and the new house. We are also getting charged interest of $500 a day on a default notice until we can come up with the money,” she said. They were forced to ask friends and relatives to help bridge the financial gap.

“You trust the system, you trust the banks. But PEXA has claimed no liability and neither has the CBA. I’ve really lost trust in this process,” she said. Ms Venn said CBA wouldn't correspond in writing and hadn't been able to tell her where the money had gone or if it would be returned. “I feel I want to pull out all my money from the bank. I don’t trust these big corporations. They don’t care about ordinary Australians.” “We are aware of the issues relating to PEXA and have begun an immediate investigation. We are currently assisting the appropriate authorities with their enquiries,” the CBA said. Another provider Sympli, a joint venture between the ASX and Infotrack, is looking to set up a rival platform.

Universal e-settlement was first proposed by the states 20 years ago and finally made it on to the Council of Australian Governments' agenda in 2008.