Find HMO and health insurance plan complaints in Illinois for 2020. Click on Consumer Complaint Complaint Ratio Reports to find rate of complaints for health insurance companies. HMO complaints are separate from Individual plans and Group health plan complaints. The worst Group Health complaint ratio for 2020 in plans that had at least 1 million policies in force, was Blue Cross Blue Shield of IL (Health Care Service Corp) (over 6% market share). Blue Cross Blue Shield also had the highest HMO complaint rate. The most common insurance complaints overall were about claims handling. Complaint record from 2020 is supplied by the Illinois Dept. of Insurance. Updated April 2022.