The High Court has dismissed an appeal in a bitter four-year, $5.2 million bullying and unfair dismissal claim against software company TechnologyOne and founder Adrian Di Marco, but the dismissed executive has vowed to fight on in a $25 million retrial.

The Australian Financial Review first reported the claims in 2018 when Behnam Roohizadegan, the former decade-long Victorian manager, claimed he was bullied, marginalised and undermined by the company from early 2016.