Coventry Health Care. P.O. Box 7370. London, KY 40742. For Illinois North and Central members. Prescription drug services: Email us or call 1-844-741-8423 (TTY: 711), seven days a week, 24 hours a day. Mental health & substance abuse care: Email us or call 1-800-423-8070 (TTY: 711), seven days a week, 24 hours a day..