On 1 January 2013 a new Regulation commenced in NSW requiring licensees engaged in qualifying activities under the Property Stock and Business Agents Act 2002 (NSW) (PSBAA), including strata managers, to hold professional indemnity (PI) insurance.
Maybe you can consider an indemnity claim? CHU has an excellent fact sheet on the new Regulation at:
https://www.chu.com.au/strata-news/2013/03/the-new-mandatory-professional-indemnity-regulation