Two class action lawsuits were filed on behalf of health care providers Thursday against Change Healthcare for allegedly failing to protect itself from a cyberattack that caused an unprecedented disruption on the health care system.

A Chicago-area mental health provider and her office, as well as a Mississippi-based obstetrician and gynecological office, filed the separate suites against Change Healthcare, UnitedHealth Group, and Optum, seeking to hold them accountable after the cyberattack left providers across the country disconnected from technology services, rendering them unable to verify benefits, send in claims, submit prior authorizations, or be paid for their work with patients, with one provider’s outstanding bill exceeding $100,000.