The Sydney Morning Herald has reported (here) on an investigation at the ANZ Bank into allegations that unsecured-debt collections staff used a fake profile on Facebook as a tool to entice skipped defaulters into providing details about themselves and their locations.
Whilst a lot of personal information is made publicly available on the internet by individuals, collecting personal information without disclosing its proposed use is a breach of the Privacy Act.
Similarly contacting relatives and friends of a borrower to either discuss the customer’s financial affairs or using a fake story to obtain personal information about the borrower could be unlawful.
You should review your collections procedures to ensure your use of social media to collect information is lawful.