The company behind one of the country’s largest home-building franchises, GJ Gardner, is facing claims it engaged in unconscionable conduct and cost the owner of its NSW and Western Australian licences $6.6 million in a bid to consolidate control of the national empire.

NSW master franchisee Colour Capital is seeking damages and further relief, documents lodged in the Federal Court on Tuesday show, in the latest high-profile battle between a franchisor and a franchisee following a similar court case between car manufacturer Mercedes-Benz and Australian franchisees.